Foliate: a modern eBook viewer with online catalogs included
With Foliate you can read your local eBooks or download them from one of the three online catalogs included.
Available on Flatpak, Snap and on most distros repositories, Foliate is an awesome application in which you can download (or buy) eBooks from three popular catalogs: Standard Ebooks, Feedbooks and Project Gutenberg.
It has all options you need: dark mode, several layouts, change font style and size, etc.
However, I see some crashes or strange behaviour, but nothing to worry about. It’s a great eBook viewer and it deserves to be installed.