In D&D 5e, there's an optional rule (which ~everyone uses) for feats, where characters can choose to take a feat instead of an ability score increase (ASI) at certain levels. All characters get ASIs every 4 levels, and fighters & rogues get additional ASI-levels. There are many less feats than in 3.5e, and the power level of the feats vary drastically. BG3 uses this system.
The lack of feats is one of the common criticisms of 5e, because many feats aren't worth the whole ASI you give up, whereas other feats are OP (Great Weapon Master, Sharpshooter, Lucky). It makes it very punishing to take small, more-flavorful feats. Hopefully in 5.5e they rework the feat system and untie feats from ASIs, so players can better customize their characters.
Weapon focus, specialization, etc doesn't exist in 5e as the system removed most small modifiers. And skill bonuses were replaced with "Do you have proficiency in the skill or not?", where your proficiency bonus slowly goes up with level. A few classes get additional skill proficiencies as they level up, but for the most part your initial skill selections are what your character is good at.
In summary, for better or worse 5e is a very streamlined system. Unless you pick a caster, you don't really get many choices as you level up, aside from deciding whether to take the ASI or choose a feat every X levels. Or whether to multiclass I suppose.