Unless your comic is your livelihood, I would suggest avoiding 3D assets as much as possible. If you don't stop using 3D assets, then you won't ever know what you need to improve on in the fundamental level. Take a step back from creating comics and just work on small illustrative works. Like, draw strangers and their environment or your favorite OCs in their worlds doing stuff. Experiment what you want in your comics moving forward. Once you publish that first chapter it is an art style choice, and you have to commit to it if you want consistency in your work.
This is a more personalized suggestion from me, but I highly suggest looking into SamDoesArts work, how he paints backgrounds is eye opening, and that is coming from someone who used to hate doing backgrounds. Nowadays I can't even draw a character without the backgrounds, if I can't draw the background, then it doesn't feel like the character is worth drawing. That isn't an end all be all, so I encourage you to look into works that you love and study them. When people say study others work, they mean try to replicate their art style and background, putting yourself in that artist's shoes. Ghibli Studio has some really good backgrounds to study from as well.
Pro tip: Make terrible backgrounds. No, seriously, draw that wonky furniture. It's one thing to be able to visually identify odd shapes but your hands are just as important in this process. Let your brain and hands communicate even if you feel like ripping that art piece apart.
I hope this helps a little!