SetScale works on per frame (and on its children). So using it on UIParent will scale your whole UI. But you can also use it on other frames, like CharacterFrame. So running something like
Code:
/run UIParent:SetScale(0.5333); CharacterFrame:SetScale(1.875)
Will scale the whole UI down and then scale only the charachter frame back up as it was in 1.0 scale. If you first want to scale everything down and only specific frames back up, or only scale specific frames down pretty much depends on what and how many frames you want to scale.