@sgunhouse not a bad idea, but it's slower than just use the secondary mouse button and click on Magnify image. It's very convenient to use.
@derDay that somewhat could do in the meantime, although it can become a bit messy in certain pages with lots of images, the idea is a bit similar.
I still hope that a similar feature is added. For anyone who uses MS Edge, it's very easy to test and how convenient it can be.
I find myself clicking the secondary mouse button quite often in Vivaldi trying to use that feature until I realise that I can't.