Supported devices
Most phones from the last few years support eSIM, but two things need to be true: your device needs eSIM hardware, and it needs to be unlocked from your home carrier.
iPhone
iPhone XS, XR, and newer support eSIM. Any iPhone bought outside the United States is typically already unlocked. To confirm, go to Settings → General → About and check for an EID or look for "Mobile Data" support for a second eSIM plan.
Android
Most Android flagships from 2020 onward support eSIM, including recent Google Pixel, Samsung Galaxy, and select other models. Check Settings → Network & Internet → SIMs, or search your exact model name plus "eSIM support".
Is your phone unlocked?
A locked phone can't add a second eSIM from another provider. Contact your home carrier to confirm your device is unlocked, or check Settings for a "carrier lock" or "SIM lock" status.