Reset iPhone before selling

This morning I got a notice that somebody used my Apple ID to log on an iPhone 5c.

I don’t have an iPhone 5c.

I did recently sell an iPhone 6+ and an iPad Pro.

Before I sold them I used the erase and reset feature. Should I have done something more to make sure all my stuff was off them?

via ehMac.ca https://ift.tt/34TRrgW