Since some cards represent very high yield topics and others not so much, it would be nice to have something like a yield meter that could show how important each card is during review.
The high yield tags are good but aren’t very helpful during review when cards are mixed
You could add a flag to those cards that have a high yield tag.
That’s how I “mark” them 
The flag shows up during the review in the upper-right corner and is a visual hint.
I use red for high yield, and yellow for low yield for example.
Not the exact feature you’re requesting but you can use the AnKing Note Types (Easy Customization) Add-on as explained here: The AnKing Note Types and Add-on Youtube with Colorful Tags (+ Hierarchical Tags) Add-on