Outlook 2021 does not have a People icon, but it does have Contacts. Click that
Under Contacts is, … Address Book. No Contacts again, no anything else. Click Address book.
Double click members
Click Add Members
Select one of three options, I selected New E-mail contact
Disable the option to Add to Contacts
Edit in the name and email address
Click OK
A name not in the contacts list was added.
Thank you for the link to the instructions that got me there.