How to zoom in and out content in a specific iframe only?
I know I can use Ctrl plus + and - to zoom in and out the whole page. but now I only want to do it to content in a specific iframe. Is there any way can do that?
It's all or none that the default. If you want specific zoom that would require 3rd party software to do that.
You can possibly try to hold the Ctrl key and rotate the mouse wheel when you hover the iframe. Something else you can try is to open the iframe in a new tab via the right-click context menu (This Frame -> Open Frame in New Tab).
I don't think there is a built-in feature for this, and in a quick add-on search, I didn't see one. cor-el's suggested workaround (right-click > This Frame > Open Frame in New Tab) is what I would usually do.