Yes, you can do that! If you already have one eSIM on your phone, you can still add another eSIM. And nowadays, operating systems allow you to add multiple eSIMs to your phone.

However, you can only activate one eSIM to work simultaneously with one physical SIM card on your device, that is if your device support Dual SIM, or else you can only use one SIM at the same time. 

Starting from the iPhone 13, Apple has allowed the operation of two eSIMs simultaneously while the primary physical SIM card is turned off. Gradually, eSIM will replace physical SIM cards due to the numerous benefits and features it offers.

eSIM ONE - One touch to the world

How to install eSIM: https://esimone.com/check-device

Check Compatibility: https://esimone.com/check-device