Khan Academy has a digital SAT prep course that is officially recommended by College Board (the people who write the SAT). You can access the course and sign up for free live tutoring for the SAT here: Khan Academy Digital SAT
The digital SAT has this version of Desmos embedded: SAT Desmos Calculator
There are many videos and prep guides, but these three creators have highly rated videos on how to answer many common SAT questions using Desmos.
This video is 38 min long, but very informative!
This is a quick 9 min video
This video is 2 hours long, but the creator says he scored 800 on the SAT Math