The Europe (31 areas) eSIM covers 31 countries: Austria, Belgium, Bulgaria, Switzerland, Cyprus, Czech Republic, Germany, Denmark, Estonia, Spain and 21 more.
If your eSIM supports top-ups, a Top up button appears in My eSIMs once the eSIM is in use. The extra data goes onto the same eSIM, usually within a few minutes. If it doesn't, buy a new plan; it arrives as a new eSIM.