Saying “no offense” doesn’t make anything less offensive. It just warns them it’s coming.

Two words at the front of a sentence cannot change what the sentence does. If anything they make it land harder, because the other person braces and then gets hit anyway. People reach for that opener when some part of them already knows the comment is unkind, which is useful information about the comment.

Treat the phrase as a signal rather than a licence. When you feel it arriving, stop and ask what you are actually trying to say. If it is true and worth saying, say it plainly and kindly. If it is not, you have just saved yourself an apology.