I wonder if I can purchase and activate an eSIM on my iPhone Xs Max before I leave for UK from the United States?
Are you a US citizen? Do you already have an EE contract SIM? You can only convert a contract SIM to an eSIM. As a non-UK resident you would be unable to take out a contract with EE as you would have no UK credit history.
I'm guessing you were thinking of getting or using a PAYG SIM over here. You cannot have an eSIM on PAYG.
@wangs99. you can not use an esim unless your a contract customer.
Welcome to the EE Community.
If you can move your current plan to your eSIM, you could then pick up a physical EE SIM from an EE Store when you arrive in the UK.
Hope this helps. 🙂