lost iphone

You can't use Apple's Mark as Lost option if Find My isn't enabled buy you can contact law enforcement and your carrier. See the following Apple Support article for information on things you may want to do if Find My isn't enabled: If Find My iPhone or Find My iPad isn't enabled on your missing device - Apple Support

Contact the police, your wireless carrier, and if applicable, the Lost & Found department of the facility involved.

(236280)

RJG1000 wrote:

how do I mark a device as lost without find my activated?

You don't.