Got turned on to something called the Homebrewery. If you want to make TTRPG supplements that are D&D-friendly, this site looks like it’ll work out for you pretty well. It’ll generate pages, columns, table of contents, tables in general – my only concern is art, because I don’t know what I’m going to use for it. I won’t use AI or rip off other people’s, but I don’t know where to find the right kind of public domain clip art. There’s only so many ways you can draw a Book Man Was Not Meant To Know.
Still, this is gonna look a lot better than the first one I did. I may grab that PDF and reprocess it, in fact.
I like Pixabay, but there are others, especially if you’re looking for something specialized.