Look up rotoscoping and

Look up rotoscoping and continuous line rotoscoping to find out more information. You’re doing the same thing as those, but with less coverage of your video layer.

See the link below for an example using ToonBoom software. The software is very different but the process is exactly the same in Premiere Pro / After Effects.

https://www.toonboom.com/resources/tips-and-tricks/going-bananas-rotoscoping