International (Europe) calling

This fall I'm going on a Mediterranean cruise.  It leaves from Athens, stops in Albania, Italy, Malta, France and ends in Barcelona.  I can probably get by with WhatsApp and wifi on the ship but I'd like to have the capability to make a call or use data while on land, in case I never need to.  Xfinity has a $10/day plan but it's very limited on data.  I don't know what international roaming charges are but I suspect they are high.  I've got an iPhone 15 so it has an eSIM.  Any suggestions or links will be appreciated.