My SIM card tray won’t pop open on my XS. I am afraid of pushing too hard. Any suggestions?

See this support article for how to remove or switch the SIM card in your iPhone --> Remove or switch the SIM card in your iPhone - Apple Support

You have to press pretty firmly. If you have problems take it to an Apple service provider and ask for assistance.

Go to this page to find your nearest Apple Authorized Service Provider (AASP) or Apple Authorized Distributor (AAD) --> Find Locations

How to make a Genius Bar appointment

1. Go to Genius Bar Reservation and Apple Support Options - Apple

2. Go to "Get hardware help".

3. Select your hardware and continue selecting options requiring replacing parts until you see "Bring in for Repair"

4. Sign in with your Apple ID

You may want to take it to an Apple Store or cellular provider, they can take a lot of force to pop them open, but I understand that you don't want to break anything.