mu_meyy Each EA Account can only be associated with one platform account of each type in its lifetime, (while it is a bit confusing, you are able to unlink a platform account from one EA Account to then link it to another EA Account).
For example, if you have the EA Account "player" and are now using the EA account "user", you can unlink your Steam Account from the "player" account and then link your Steam Account to the "user" account, (but it won't transfer your Apex progress and/or data over to the "user" account", as that is tied to the "player" account).
If you choose to link your Steam Account to another EA Account, just know that the second EA Account won't be able to be linked to a different Steam Account in the future either.