I have to deal with this so often at my job. The trainer at my store is obsessed with alpha theory and delivers harsh verbal (like, screaming "AHHH-AH!") and physical (jerking gentle leaders all over the place) corrections, and she works in one of playrooms of the hotel, so she's always around. I have to try to compete with that, and suggest that clients stop giving their reactive dogs harsh corrections and move at the snail's pace of cc.
My favorite thing to do is recommend books or better yet buy some one a book. REALLY. If this person is close to you and they/their dog is part of your life shell out $20 for a good book as a "new puppy gift", maybe along with a toy to disguise it. "After You Get Your Puppy" is my fave! I bought it for my completely clueless friend who got a puppy on a whim, and he actually read it. And he actually applied it, and bought more books by Dr. Dunbar. I find it so hard to express everything that I want to say about training to people in conversation, whereas books are full of information and if some one buys you a book you have to be pretty rude to not read even a little bit of it.