

You can improve a skill by visualizing your performance of the skill.
But you need to have the experience beforehand to be able to understand what you’re visualizing.
So - absolutely not.
There’s enough people locally who die that it seems reasonable for me to project that thousands die globally each year because they have no clue how to swim, but other people are there having fun in the water and how hard could it be?
Hitting particularly cold water makes it even worse.