This tutorial is mostly for Flashthemes.
First, Install flash player. You can do this by installing it through the aur package also Debian or if you cant find it through your package manager, check the flashbuilds folder
Next, install a chromium build that is under chromium 88. You will need to disable the sandbox or else chrome wont load webpages.
You will also need to specify the --ppapi-flash-path or it will not load flashplayer.
./chrome --no-sandbox --ppapi-flash-path=/usr/lib/PepperFlash/libpepflashplayer.so
( replace chrome with the file name if on the appimage version )