Heyahh it's good idea to try out other programs just like the other suggestions :))
I'll be that one post that wholly recommends Sketchup haha.
It's the only 3d program I know and the most I'm comfortable with, its pretty easy to use once you get used to it
I agree too that there might come trouble when using models from the 3d warehouse if your comic is already earning (but to be honest I haven't seen anyone getting in trouble for it? Tho it's still best to be careful).
The safest way in my opinion is making your own background from scratch, using models like furnitures/material (from the warehouse) to decorate the room or building is fine too. If you have no idea how to create from scratch, try to deviate the original model and tweak it in a lot of places so it would look a lot far different (this is the scam method
don't hate me for this pls, most webcomic artists are also guilty of this. I have to admit this.)
Most creators use sketchup as their bg and all the while earn from it. I just imagine they've done what I've suggested just now. Also, I've had an official webtoon creator commission sketchup backgrounds from me, still doing so to this day.
So yeah, using sketchup is not that all bad. Just don't take credit for the models. Whatever you're decision is, I wish you the best of luck!