2ndLine provides the virtual number(s) which work using VoIP technology. VoIP is totally separate from eSIM. eSIM is an advanced version of SIM which is used to access traditional telephony services.
The virtual numbers provided by 2ndLine allow us to make and receive calls and texts from real numbers.
You can use 2ndLine instead of configuring an eSIM, however porting a virtual number provided by 2ndLine to a real network and reverse is not possible.
The use of an eSIM and 2ndLine in parallel does not make any negative impact on the other side. So if you are already using normal SIM and eSIM on your iPhone XR or so, 2ndLine works for you as 3rdLine number! ?