This guide will show you how to type in red text. This is only clientside and works sometimes not everytime.
The First and Last Step
So all you need to type is either "<" or ">" once it gets picked up as a censored word, bam you are good to go. Just start typing and check if it works, it wil affect both enemy, you and teammates. I don't know why it's like this but yeah.
Look at the bottom right of image and you can see it gets censored.