I see a lot of information in the opposite direction: if you have a PS4 linked epic account you can't use it on Switch. However I'm wondering if you played on Switch first can you then play on PS4?
Play a Switch Fortnite account on PS4
fortnite-battle-royale
Best Answer
yes, you can link your accounts. In order to do that, you have to go to epicgames.com with a PC*, sign in, go to "account", then "CONNECTED ACCOUNTS", and then link it from there.NOTE: there is a small possibility that you will lose your progress, so I suggest that you link it with a test account first