Hi ZeeshanGhause,
Agree with Owen.
Since the email is stored in the description of multi option set field, I'm afraid you have to create a plugin to obtain it.
If you would use no-code way, like workflow or power automate, we can only set the email in the steps, not store email in the field.
Here is a demo. I take the contact entity as an example.
I have a multi option set field which has 3 options and a two option field to indicate whether to send emails.
Whenever the user selects the options of the multi option set field and select two option field as Yes, D365 will automatically send an email to the selected employees, and set the two option field to No.

Go to https://us.flow.microsoft.com/, select the D365 environment.
Create an automated flow, set it as follow.
