Can I have both a physical SIM and eSIM active at the same time?

This is going to be dependent on your device. Only devices that support dual SIMs will allow you to have two SIMs active at the same time.

iOS: An iPhone XS, iPhone XS Max, iPhone XR, or later with iOS 12.1 or later

Android: Since the Android market is so varied, we don’t have a list of Android devices that support this functionality. The best way to find out if your device supports dual SIMs would be to read your device’s information booklet, Google your device’s specs, or speak with the carrier that issued your device. You can also go into your SIM manager to see if you’re able to have two SIMs turned on at the same time.

With Samsung phones, typically the newer models will be able to support this feature.