How do i activate find my AirPods?

If you have the activated Find My on your iPhone, iPad, iPod, or Mac,

Set up Find My on your iPhone, iPad, iPod touch, or Mac - Apple Support

then that will list the AirPod earbuds as well,

if those were initially registered to a device with the matching Apple ID.

To disassociate AirPods from any old Apple ID, you’d have to do so through Find My, before linking to a new Apple ID.