Why am I seeing outgoing calls that I did not make?

Do you share an Apple ID with anyone?

Then calls in the Recents section of the Phone App will be either calls you make or received.

Calls you make, will have a small Phone icon with an arrow pointing away from the phone.

Calls you receive will have no icon

Calls you receive but missed or did not answer will be in red.

WhatsApp calls and FaceTime cals will also show up there.