post https://a.klaviyo.com/api/profiles/
Create a new profile.
If you use a phone number as the profile identifier and SMS is not set up in the Klaviyo account, you'll need to include at least one other identifier attribute (email or external_id) in addition to the phone_number attribute for the API call to work.
Rate limits:
Burst: 75/s
Steady: 700/m
Scopes:
profiles:write