I get what you’re saying here. I’ve been playing since Sims 1... (technically. I was super young when i discovered it and even then, when I did discover Sims, Sims 2 was already more than halfway through. But I digress )
...and to be honest I think that when first starting out with a Sims game, no matter the iteration, your sims will indeed look like crap. At least mine did. But this is based on my own opinion and my own experience with the game. There will always be others with better looking games than me but here’s what I think would help:
To start with, get default replacement CC. Items like default eyebrows, hair, eyes and skins are HUGE game changers when it comes to the look of your simmies.
Also, getting lighting mods will bring a whole new aspect to the game you never would have imagined. I know it’s just simple lighting but dang if it doesn’t make things look prettiful <3
https://66.media.tumblr.com/5321ea02fb725e1526f783f55284d684/tumblr_phagx9Xrfo1xq9hdmo1_1280.jpg
You don’t need a whole bunch of CC, really. Like others smarter than me on here have already pointed out, playing around with the sliders is the key to having interesting looking sims. But admittedly, having default skins, eyes, and whatnot does help. Just my two cents :)