Many small databases or 3 large ones

I have a blog that allows quite a lot of user customisation for this to work I have a main database table that holds all the things like the order to render the blog in what roles can view each section etc, then each post can look completely different and hold all different data so it needs some fields a second post would never use a third table is pure images to be inserted into the posts.

Im looking for advice on the tables that would hold the posts, as there would be a lot of designs would it be better to have say one big database table with 100 columns (not sure the exact number) or would it be better to have tons of small ones

The issue is I never know which table I need until after the parent table runs the query and repeats, so then I condition a column in the parent table to use the correct small database for the post

Is using more smaller databases advised for this or would I be better using a large database but having to also collect un needed columns?

Hope that made sense