Actually the S21 series does have eSIM support in Canada.
But I don't think that there's a way to do what the OP was asking.
I searched the keywords "Allow All SIMs To Use Data In Calls" and found this thread.
I am using S22+ Dual Sim (SM-S906E/DS) and want to have data on Sim 2 NOT disconnected when receiving a call on Sim1.
My both Sims have VoLTE enabled. Using either Sim for data, a call coming to the same sim doesn't make data disconnected. However, a call coming to another sim than the one with data would make data disconnected. Searching around I understand that I would need to enable the option "Allow All SIMs To Use Data In Calls" in Settings > Connections > Mobile Networks. But there isn't such an option in my phone Settings. What can I do?
Yes, I have the same question for my S22. I want to continue to use Sim1 for calls/text but my esim for data roaming when traveling to the USA.
You can change the default calling Sim for each individual contact. Tap on the contact and then tap the information button "i". Then right under the name and number you can change the default calling sim to your Sim1.