Ideally I'm looking for quantitative research on this, if it exists, but I'd also be interested in anecdotal evidence from observing user behavior.
To what extent is the average user aware of, and comfortable using, the browser zoom feature? This can be either via menus, Ctrl++/-/0 (or Mac equivalents), or Ctrl+ mouse wheel?
The reason I ask is because scaling issues seem to be pretty commonplace with multi-screen setups where one screen has a different pixel density. To what extent should this be a UX concern in terms of optimizing for all possible display setups, or to what extent will users "instinctively" know they can just zoom in/out as needed?