Only Audio. About graphic, I think that must be something with incompatible patches, probably rebuild clover would solve this. Unfortunately I don't have time and knowledge :-/
Well its actualy very simple just download it from store.
Open app and install it.
Instalation takes about 1-1.30h.
During installation computer will restart few times.
After instalation you will see many more new boot options. Select one without addons.
Your mac partition wil be converted to new format. Due compatiblity problems I sugess you to the convert APFS partition back to HFS+J with this application: https://www.paragon-software.com/home/apfs-hfs-converter/
For audio you can try: sudo touch /System/Library/Extensions && sudo kextcache -u /
If this doesn't work simply install lates voodoHDA