One great advice I've heard is that, before even going into a debate, you ask someone "What would it take for you to change your mind on this subject?"

People won't change their mind if they don't have an open mind to begin with, or if they're not open to debate on a subject matter in the first place.

A lot of people - online and off - will engage in debate for debate's sake, even though all parties involved are not willing to change their opinion. They just want to be heard.

I mean who here would have an open mind about e.g. flat earth or whether the Holocaust actually happened (to invoke Poe's law)? I sure don't, and I don't feel guilty about it either; I don't need to consider anyone's point of view if I find their opinion morally reprehensible, and if they strongly hold those beliefs and are unwilling to accept alternatives, they're not worth the effort or time. They can go back to their echo chambers.