Open the Calendar app on your iPhone.
White Frame Corner
Click the ' +' icon in the upper right corner to create a new event.
Add Title and Location for New Event.
Now tap on Invites.
Click on the '+' icon to add contacts,
Add the email or contact number of the person you want to invite to your event.
Tap Done to send the invitation.
If we want to send an invitation for a unique event (birthday, dinner, work, etc…)