I’ve been to some actual speech therapy, not that useless school shit, but what she taught me is smooth and steady onset, and it actually works. First your need to learn to talk really slow, not in everyday conversation but as practice. Just choose a random paragraph and practice reading it slow and every word should start smooth and end smooth along with barley annunciating the syllables. Do this until your good at it(with no stuttering), then slowly start speeding up. You have to do this every single day until you rewire the way you talk. It takes a couple months of practice but it really helps. Keep in mind my speech isn’t perfect but it’s definitely a lot better than it was.