What am I talking about?
https://github.com/Suwayomi/Suwayomi-Server
It's a lightweight docker/container/program for grabbing manga and comic from various sources such as mangadex, readallcomics, weebcentral etc and putting it on your desktop. It has no ads, it can download chapters and store them as individual images or chapter cbz.
It will even update automatically when there are new chapters of a series you bookmarked
You need to add a repository. Under settings ,browse ,extension repository
I use https://raw.githubusercontent.com/keiyoushi/extensions/repo
Then you add sources from there under browse, extensions.
It used to be easier and sources like mangadex were usually auto included but big manga sent a c&d to tachiyomi, the predecessor of this project claiming they were aiding piracy by doing so they had to separate it