I was doing this with documents only when I was using Veracrypt, which forces you to have a fixed volume size and I had to pick and choose what to put inside. When I discovered Cryptomator, which uses a directory and can grow as much as needed, I decided that there was no need to think about what I should encrypt and what not: let’s just put everything inside that folder and be done with it.

Use whatever cloud provider + encryption on your side. That way you don’t have to trust them.

I use pCloud (based in Switzerland) and what I sync is a Cryptomator vault. You have other options, such as VeraCrypt, etc.