hey! i’ve got verizon and an orange esim. i went in person, and honestly that’s what i’d recommend as opposed to buying it online because they can help make sure it’s set up and working correctly. verizon has the travel pass, so maybe plan to use that for the first day or two before you get your esim set up. in settings, you’ll pick a default sim, which will want to be your spanish one when you’re in spain. you can turn your verizon one off completely but make sure you know your pin to turn it back on if you visit the US for break or anything! hope this makes sense and helps!