time travel with POC character going to times and places with no or very few POC/people that look like them

[Spockles]

(sci-fi/fantasy/historical fiction, etc)
Something like the movie version of A Connecticut Yankee in King Arthur's Court featuring the African American girl.

[Ann aka Iftcan]

Lavender-Green Magic

[Peter]

This is a minor element in Terry Pratchett's Johnny and the Bomb, where four "modern" British kids (mid-90s, really) go back to England during the Blitz. One of the kids is black and he encounters a bit of difficulty. I wouldn't read it just for that scene, but it's a great read anyway.

[Spockles]

Thanks for the suggestions!

[Kaion]

Kindred
A Wish After Midnight

This entire Tvtropes page may also be of interest:
http://tvtropes.org/pmwiki/pmwiki.php...

[Ann aka Iftcan]

Ok, while not fitting the second part of your request (the only POC, or one of very few POC) you still might like Wraiths of Time.

[Spockles]

Thanks! Ooh, I shall bookmark that TVTropes page for later reading.

[Rainbowheart]

The Black Canary
The Moon Over Crete

[John]

I might suggest A Rebel in Time by Harry Harrison. The story rattles along. And in a slightly different direction, there is time-travel and race issues involved in The Guns of the South by Harry Turtledove.

[Rainbowheart]

The Freedom Maze has a MC who is mistaken for a person of color, if that counts.