Can I use two eSIMs at the same time?

Yes, you can use two eSIMs at the same time if your phone is of the iPhone 13 series, including iPhone 13, 13 Pro and 13 Pro Max and later models. Older or other phones do not support this feature.
Many phones allow you to use multiple eSIMs on one device, but only one eSIM can be activated at a time.