You could do that yes, but keep in mind that the Steam account will only be able to access the progress of the account it's connected to. So Relinking it from Account #1 to Account #2 means you will be able to access the content from Account #2 but not from Account #1 unless you were to link the Steam account back to Account #1.
Though if you want to be able to freely change between accounts, I'd recommend downloading Apex on the EA App, that way you only have to sign into the other EA Account instead of having to relink a Steam account constantly between 2 EA Accounts.
It's also important to keep in mind that whenever you relink a platform account that it's possible that you won't be able to relink it again for a period of some months. So if you were to relink your Steam account from Account #1 to Account #2, you would likely not be able to link it back to Account #1 for some months. Hence why I'd recommend downloading Apex on the EA App so you only have to switch EA Accounts to access the different progress.