Most dogs know how to swim instinctively, so most likely it will just be a matter of making sure they have a place they can safely get in and out of the water and ensuring it is a positive experience for them. Depending on the dog they may need some encouragement or reward to get into the water, of they may just enjoy it without anything extra.
There are some dogs that don’t instinctively understand swimming though, and if you have one of those (it’s usually the solid muscle breeds, they tend to sink easily) you would need to put in more effort to actually teach them. I’ve not had that issue myself so I can’t really advise, but I think it involves supporting them for a while as they figure it out and gradually removing the support. I had a friend who took her dog to swimming lessons, I think she said they have flotation vests they use.
The problem with that idea is that once you reach a certain number of people you stop getting diverse views and just get the same type of views over and over. Large groups on a platform like Reddit prioritise fast and popular responses. Quick quips and memes posted by people who are spending all day scrolling will drown out any sort of reasoned argument that takes time to type and participation by people who only log in occassionally.