There is a good way to install Latex to avoid many junk of libraries under Linux:
apt-get install --no-install-recommends texlive apt-get install --no-install-recommends beamer
With this method, it can run well on any Linux machines, even on a low power raspberry PI. With this installation method, you can be sure that your book editors or manuscript publishers will not complain of not being capable to make a PDF out of your source file.
In beamer there is a lot of default theme with this minimal installation method.
However, I searched into the directory /usr/share/texlive/texmf-dist/tex/latex, but it seems that there aren't default themes for Latex, for instance reports, articles,...
It is actually good, yeah, because we asked for a minimal installation.
I am expecting that I could have maybe not found if there are few beautiful latex default themes, for articles, books,... that are in all Linux distros for sure.