How do i get a Snow fox in minecraft ps4. i have tried commands and they don't work

The only way to get a snow fox in bedrock is to use a spawn egg in a snowy biome (meaning it's impossible to do it in a flat world because you need to be in the actual biome, you can't just place snow). Once you have successfully spawned one, you could use a structure block to save the fox entity to a structure and then spawn it in via the structure command.