The easiest time to install your Latvia eSIM is at home, days before you fly. You buy the plan, get a QR code by email, and add it to your phone while you still have your normal WiFi. Nothing turns on yet, so you will not waste any data. You just leave the new line installed and ready.
First check that your phone is unlocked and supports eSIM. Most iPhones from the XS onward and most recent Samsung, Google Pixel, and Motorola phones work fine. On an iPhone go to Settings, then Cellular, then Add eSIM, and scan the code. On Android look for Network and internet, then SIMs, then Add eSIM. Label the new line something clear like Latvia so it is easy to find later.
Pick your data size before you buy. For a short city break with maps and messaging, the 3 GB for 15 days plan at $2.10 covers most people. If you stream or share a hotspot, the 5 GB for 30 days plan at $3.33 gives you more room. Heavy users on a longer trip should look at the 10 GB for 30 days plan at $5.99.