Buying iPhone online in the USA and shipping to Europe

Don’t. Though there is a non-zero chance the warranty would be honored, it’s likely you would not be able to get it serviced at all outside of the US.

In addition, the US model iPhones are eSIM only. they do not have physical SIM slots.

I agree with Tim; it's not a good idea. But if you insist on buying in the US anyway, Apple will not ship internationally, so you'll need to have a US address through which to receive the iPhone. Then you will need to ship it overseas yourself.

Regards/

In addition to what varjak paw explained, don't try to have the phone shipped to one of those companies that advertise as being able to receive goods from companies that won't ship internationally and then ship them for you. Apple knows who these companies are and will cancel orders if they are found to be shipping to their addresses.