Hi CJE1201,
Thanks for coming to Apple Support Communities for help today.
This is information you should have from your new carrier. You will likely need to contact them for further help if you don't have it, but you will want to review the information regarding setting up an eSIM here: About eSIM on iPhone.
You may even be provided with a QR code to set up the new service. If not you will have to set it up manually with the information they provide.
"Enter the eSIM information manually if necessary
- Contact your carrier to get the eSIM details you need to enter.
- Go to Settings.
- Tap either Cellular or Mobile Data.
- Tap Add Cellular Plan.
- Tap Enter Details Manually, at the bottom of your iPhone screen."
Have a fantastic day!