can i change the line terminator using php? cause everytime someone sends a pm in my game or posts a message on the ingame forum if they have any enters in there it doesnt enter but returns rn

could i maybe string replace it? so far all i could do is have everyone put [br] and replace that with <br> so that it would go to the next line

so is it possible? or am i in the wrong place on the forum -_-