This guide will let you know how to LINK your EA Account to STEAM for APEX LEGENDS.
1- You have to open up your browser, search apexlegends.com, and open it. On the top right side of your screen, you will find a small profile logo, you need to click on it and then click on sign in. As you want to link your EA account to Steam, you have to sign in using the Steam account.
But make sure that you have an EA account before doing this. After signing in using your Steam account, you have to give permission of linking to your EA account. It will bring you to the link page where you need to click on the Link button.
After this, you will be brought to the Apex Legends page. Click on your profile on the top right corner of your screen and then navigate to account settings. Then click on the connection and you will find all your accounts.