Open the Contacts app or the Phone app on your iPhone
Tap the contact you want to export
Tap Share Contact
Choose how to export it, such as Mail, Messages, AirDrop, or Files
To export multiple contacts, use iCloud on a computer
Go to iCloud.com and sign in with your Apple ID
Open Contacts
Select the contacts you want to export
Click the gear icon
Choose Export vCard
Save the exported file to your device
To export all contacts, sync contacts with iCloud first
On iPhone, go to Settings
Tap your name
Tap iCloud
Turn on Contacts
Wait for sync to complete
Export the contacts from iCloud.com as a vCard file