Sadly no way to do this with Summoner's name, but some of them use rare characters.
You can do color in your ALLIANCE NAME, scanning thru Alliance Leaderboards you’ll occasionally see some in color.
But for individual player name, you’re probably correct. Same with Ally TAG I think. Assuming that's because those are more of an indexable like item, as opposed to Ally Name which is just a Text field.
Comments
For example red:
[FF0000] Text
https://forums.playcontestofchampions.com/en/discussion/307453/how-to-edit-this-in-color#latest
But for individual player name, you’re probably correct. Same with Ally TAG I think.
Assuming that's because those are more of an indexable like item, as opposed to Ally Name which is just a Text field.