I’ve had Golden Retrievers that taught themselves to swim quite easily and naturally, first wading in a pond and then they just start swimming. I never heard of giving a dog swimming lessons. Maybe only certain breeds take well to the “doggy paddle”????
Interesingly, I did have one Golden who absolutely refused to swim. He would wade along the edge of the pond, always refusing to go very deep even as he watched his brother merrily swimming around the deep parts of the pond. It was quite a wonder to see how many times he could watch his brother swim and yet never decide to join in the fun. His brother would fetch sticks and balls all over the pond, but he would only try for them when they came within reach in the shallow waters.
When we built the new dock, we hired the guy who could build a decent dog ramp. Our dogs love the water and never had a lesson in their lives. The cats, not so much. They’re embarrassed and ticked off when they fall in.