emma8094 Your Apex progress and data is stored on your EA Account, so your Switch Account would need to be linked to the same EA Account as the Xbox and PlayStation Accounts to then access the same Apex progress and data that those two accounts have access to.
If your EA Account had been linked to different Switch Account before in its lifetime, it won't be possible to link another Switch Account to that EA Account, (and the same is true for all other platform accounts as once linked, it creates a lifetime link to that platform account).
It is also important to know that unlinking your platform accounts can also cause a loss of some, (or all), of your Apex progress and data, however if the Switch Account has nothing to lose, then you wouldn't need to worry unless you were to unlink your Xbox and/or PlayStation accounts.
Note: Apex progress and data also cannot be transferred, (or merged), to another EA Account, so in your case, your Xbox and PlayStation's connected EA Account is the EA Account you would want to link the Switch Account to.