Examine the fridge horror more often. Venus, as Codename Sailor V demonstrated, has access to poison gas boiling at hundreds of degrees Celsius (800 F, 460 C) with a suffocating density 93 times the atmosphere of the Earth (about the pressure nearly a kilometre under the surface of the ocean) remember, one of the things that makes us shudder at the First World War. That would be absolutely horrifying to go against. People execute other people with electric chairs at a far lower threshold of watts, volts, and amps than what Makoto is capable of inflicting with just a thought. She would incinerate just about anything she wished. Ever seen the Green Mile where Percy didn´t use that sponge? Yeah, that would be a lot more like what it would be like to go against Sailor Jupiter.
Mercury controls water. As anyone who knows about science, as Ami certainly does, there are many states of matter. Water is found in a huge variety of things, from about 60% of your body, really the body of any living being, to water in just about anything made of concrete. What happens if she were to think about freezing it or boiling it, or much worse, plasma? That would probably cause a building to explode, certainly freshly poured skyscrapers, and would instantly kill you if she boiled all the water from every cell, blood vessel, organ, both of your eyeballs and both of your ear canals, the water in your stomach that the acid is a solute within, and so on. Or melting a glacier or snow into water or sublimating it into a gas, which would turn a block of ice into a bomb, as you could do at the North Pole vs Beryl.
This also happens to invoke less of a magical thought, at least what the mechanism of the action is, even if the cause is still magic, making it feel more real I think. We know as adults what these phenomena are, at least from a mechanical and chemical perspective, much like Star Wars how things like a blaster bolt has some real life counterparts that could plausibly be called a blaster such as certain high powered lasers, or at least we can conceptualize the things necessary for it to happen such as a battery, laser, or magnetic coils generating plasma.
Emphasizing loss more might work well, such as how Mamoru searching for Chibiusa in the Infinity Arc when she left the amusement park. Remember that he knows that he will have been a father, treat it a lot more like a father terrified at the experience of losing their child. It was also dark when he found her, and brightly lit when he realized she was missing, so that was the better part of three hours, probably more. Anyone who has been a parent who sincerely loves their children knows how bad that feels. Hotaru should probably have some kind of positive memories of when she was Dr Tomoe´s daughter that should become scrambled after her reincarnation and potentially lost. Usagi´s parents and brother should be worried sick, as should Rei´s father and grandfather about where they could be in times of tumultuous chaos. The downfall of Silver Millennium could go into more detail in this bane. Perhaps Beryl´s army is in position outside the walls of Silver Millennium and are launching the final assault of the city, ready to sack it, with a long siege cutting off supplies and so you see disease, starvation, and comforts wither away, people turning to heavy drink, and so on.
Galaxia could be a lot more intimidating. Introducing her more so as a dictator, as she is appropriately titled, with her wars being portrayed much as Attack on Titan portrays the extermination of entire races of people. A sadistic choice perhaps, that she will kill 80% of everyone on a planet and take another 10% as slaves and the ones who rat out their friends and neighours and family will be the chosen 10% to remain, in a collaborationist system that will make people think of Vidkun Quisling and his puppet regime. Galaxia´s PGSM song Dictator´s Legend also makes reference to natural selection. And in this sense that she uses it, that becomes a hell of a lot more chilling when you know just what Darwin´s ideas were misused in our world to do, with eugenics and ethnic cleansing and worse. That will certainly remind most adults of that reference and make them really way more scared of what happens if Galaxia wins.
Also helps if the city is on fire and in ruins and it either sounds completely silent lest for gusts of wind caused by the firestorm or else sounding like heavy artillery barrages (Verdun saw a million shells fired in ten hours at some points in the battle in an area only about 50 km wide and 10 km deep by the Central Powers), even if caused by other things associated with battle like the senshi and their enemies blasting away at it. A group of girls in sailor suits doesn´t sound so intimidating until you see what they can do in full.
You could also emphasize the role of the Senshi as child soldiers too, and their reconciliation of what was called shell-shock with their attempt to be normal girls, but facing the immense difficulty of doing so just because few others know what it is like to be a soldier, to fight, to be wounded so grievously on many instances but to be dragged back to the realm of the living to fight once more, to see their dearest comrades die in front of them, in some cases even their own children vanish by their very eyes. And to some degree, even take joy from the thrill of an adrenaline rush when you defeat your enemies even if it means killing a sentient creature, a sensation many soldiers report in real life such as soldiers in Vietnam who say they loved lighting up an entire valley with napalm and it is hard to understand that feeling and the power that comes with martial might, the impunity it can give you, and having to control and restrain it lest you murder others or non combatants.
It might also work to give the Senshi, or some of them, more moral greyness than they already have. The Outer Senshi genuinely believing in how it is necessary to commit a murder of Hotaru in order to save billions of people, with the moral dilemma that brings. The Inners too, perhaps Mako or someone else with unfettered control over their living space, might say they will being back the stuffed head of their opponent as a war prize rather than saying their battle names as a way to threaten their enemies or scarred by past problems that make them perhaps at least slightly willing to use their powers at a low setting to extract information or as their version of justice for the crimes their enemies do in their view without going through the normal justice system. Still fighting in a cause of good but you begin to question their methods that way.
And also, add living with the persecution gay people live in many cases, like flashbacks to Michiru´s past of being bullied for her crushes on another girl as a tween perhaps, Haruka having parents that don´t give her autonomy as they would if she were straight or are suspicious of any girl who she is with even if they ultimately give in, and so on. A lot of gay people will really connect with those experiences.
