I normally just keep VSCode on the default dark theme and be done with it. But the vast number of dev.to and medium posts on it finally made me give it a try. Theres hundreds of posts out there on picking themes but below are some commands to help switch around and change things.
Change theme
After installing your 100 different themes you will want to switch between them.
Manual: File > Preferences > Color Theme
Shortcut: ctrl+k ctrl+t
Either option, opens up the Command palette and lists out all themes you currently have installed ordered by theme type.
Change icon theme
You can also change images if you wish and have installed those:
Manual: File > Preferences > File Icon Theme
Change font
You can also change your font
Manual: File > Preferences > Settings then in settings Text editor > Font > Font Family