Welcome back to "Discovering KDE features by accident":

On Plasma, you can hold Ctrl+Meta and use your mouse scroll wheel to zoom to your mouse cursor.
It works smoothly and it's neat little feature.

This appears to be a Desktop Effect feature called "Zoom" under Accessibility and you can also do Meta+plus/minus to control it! There are some settings there too.

I may have already tweak some settings there before but forgot about it. ^^'