Your eSIM is stored digitally on your iPhone. Here’s how to activate:
Go to Settings then Cellular, then tap Add Cellular Plan.
Position your iPhone so that the QR code provided by your network appears in the frame, or enter the details manually. You may also be asked to enter a confirmation code provided by your network.
Tap Add Cellular Plan.
If the new plan is your second phone line, follow the onscreen instructions to set how you want the plans to work together.
Alternatively, you can activate your plan through your network’s app (if supported). Go to the App Store, download their app, then use it to buy a plan.
You can store more than one eSIM on your iPhone, but can only use one eSIM at a time. To switch eSIMs, go to Settings then Cellular, tap the plan you want to use, then tap Turn On This Line.
If you have a nano SIM, you can use it as your second line. See the Apple Support article Using Dual SIM with an eSIM.