Theme/Site scaling

Sorry if this description is not technical enough and don't know if this will be achievable without too much work, but will give it a try to the best of my abilities.

Add theme/site wide scale/size default setting.

For example corresponding to zoom level in browser:
80% - 90% - 100% - 110%
Compact - Small - Normal - Extra Large.
(Perhaps with option for excluding Navigation & Top Bar)

Add option for user to change from the default setting, in their profile (Like with Light/Dark Theme option)