Pressbooks has several plugins that can be enabled to expand the capabilities of the platform. The main ones available are:
H5P: an interactive activity creation tool.
QuickLaTex: a plugin LaTeX rendering tool that allows for customized LaTeX notation.
Hypothes.is: an annotation tool that allows readers to annotate and comment on the text.
TablePress: a tool to create sortable tables within the text.
These plugins are maintained by organizations outside of Pressbooks, and may have updates and features that don't work with other plugins. For example, QuickLaTeX renders LaTeX within the text portion of your book and can be customized using a preamble. H5P can also render LaTeX, but it is not subject to any custom packages or preambles you have set up for QuickLaTeX.