Zerbu has a ton of presets in particular which are, I think, simply all of the base game options converted to be available to all ages. VibrantPixels, Obscurus, HellFrozeOver, StretchSkeleton, Faaeish, Luumia, and Miiko have a bunch of options, others have a few. I would strongly recommend getting custom body sliders and various presets too as these can give you more and better variation while sculpting a Sim's face and body.
(There are also mods for genitals if you want to go that extra mile.) If all of that sounds overwhelming, my initial recommendation is to look up Kijiko's 3D Eyelashes and Cien's EA Eyelash Removal Mod for more realistic eyelashes (but a lot of people have made eyelashes too Kijiko's are just the most well-known, and they're frequently updated.) If I could only have a very limited number of CC, I'd be sad, but that'd be my top pick because the one thing I hate and simply can't stand is the blocky eyelashes. There's even a foot replacement mod that has better details and definition when a Sim goes barefoot. There are also alpha clothes, alpha eyebrows, and alpha shoes. Alpha hair closely resembles Sims 3 hair if that helps. You'll have to look at some and decide what works best for you. If you want some super cute, short ponytails, Nightcrawler's Biscuit Hair is my favorite and I'd use it if I weren't into Maxis Match (MM is the term for clay hair and other CC which follows EA's style.) There are also some Simmers who create a Maxis Mix (like a mix of Maxis Match and Alpha) which has more strands and other details to combine the two styles but you may not like it as much. Alpha hairstyles tend to be more realistic: Nightcrawler and WingSims are the ones I know of and they're extremely popular, but many people create alpha. They have all kinds of mods and custom content.Yes, but you need a lot of Alpha Custom Content (CC.) Look for that term and you'll find a ton of options a lot can be found on TheSimsResource (TSR) but you can find them elsewhere, such as Tumbler and Patreon.
Plus how can one say "He has a big bulge in his crotch" or "He has a big dick" without it sounding sexual? The only other human simulation games I seen with bulges are Adult games. But there are children/ teenagers playing the game and its not really appropriate for their sims to have their goodies hanging out. Yes, boobs and butts are realism too, but yeah a bulge will probably increase the ratings. (You probably just want the realism and diversity). Then others may want it just for realism.
Most people would really care about seeing their sim in their underwear with a giant bulge. I understand a slight one to show the sim is a man.
It would be more towards the erotic side. It can be fact depending on your tone of voice and the conversation. Just as people may say "She has big boobs" or "She has small boobs". There is not really anything sexual in sayinig "He has a big butt" or "She has no butt". People have all kinds of butts that are visible in everyday clothing and it contributes to ones overall body shape. Then in Sims 4, there will be a butt slider, well that still isn't super sexual. A woman's breast size in clothes is not even erotic. Everyone notices breast size believe it or not and it contributes to a lot of body sizes, shapes, and proper physical appearence. A boob slider on the other hand is necessary because in every day life, the size of a woman's breasts is apparently visible.