The OS only ever sees one SIM on this SIM, you have an app to program the SIM you want to actually be active on the card, and that's how you switch.
https://support.apple.com/en-ae/118227
> You can have two eSIMs active at the same time on supported iPhone models. For example, you can use one eSIM for your home phone number and another eSIM for the place you're visiting.