How to make a map with a scaling variable? – January 25, 2023 at 06:24PM

I’m not sure how to word this to Google, so here I am.

I want to make a map showing how a rise in sea levels would flood the U.S., basically just putting a mask on any area less than “n” feet above sea level. I want to be able to change amount of flooding without going in and changing a variable for each state, hopefully having a sliding bar to change it somewhere on the screen. How can I do this?