More *children's* literature with POC and female main characters.
As a kid, I had to learn to relate to male main characters, even though I wanted female ones, because guess what...there weren't enough of them. I hungrily latched on to the few i had.
It's worse for Black kids.
But making white kids watch a Black Little Mermaid WILL help. (Plus she's fantastic).
Also, for white people who are aware of their difficulty relating to Black protagonists? Look for ones you have something in common with. One of the reasons I loved Black Lightning was because it had a protagonist in my rough age range instead of a 20-something. The fact that he was a Black man with VERY different life experiences didn't stop me from going "He's about my age" and relating to him that way. Easier than relating to Stargirl, who's a kid. She's fun to watch, but guess who I relate to at this point...yeah, that would be Stripesy because I'm old ;).
Ensemble casts help too.