Short answer: some phones can use two eSIMs at the same time, but this depends on the device model.
Many recent iPhones can use Dual SIM with two active eSIMs. Some Android phones can also keep more than one SIM active, but behavior varies by model and carrier software.
When your phone asks you to name or label the eSIM during installation, choose a clear label you will recognize later, such as 4S eSIM, your destination country or region, or Travel. If you did not rename it, look for the newly added eSIM, a travel/secondary/business label, or the line that shows No Number.
Using 4S eSIM with another SIM
- Keep your primary SIM active if you need calls or SMS.
- Select the eSIM label used for your 4S profile as the mobile data line.
- Turn on data roaming for that same eSIM line.