What happens to a lost iPhone after remote erase?

Note that thieves are very unlikely to provide the conditions the phone would need to keep reporting its location. Also, even if one saw a location, it would be very unwise to go there to confront the criminals personally. One might lose a lot more than just a phone.

Hello standash22,

From AI:

If your iPhone is marked as lost and then erased using the "Find My" app, it will still appear on the map in "Find My" or icloud.com/find. However, after being erased, you can no longer access the data on the device, but activation lock will remain, requiring your Apple ID to reactivate. 

For more detail see this:

If your iPhone, iPad, or iPod touch is lost or stolen

Good luck.

Using Find My to track the phone after the Erase requires the phone to be running iOS 15 or higher, which the OP’s phone would have been.

Even on older phones running iOS 14 or below, I believe the Activation Lock would remain to frustrate the thieves as long as the owner did not fall for “phishing” attempts or remove the phone from the list of devices associated with their Apple ID.

What happens if I erased my iPhone after marking it as lost?

Nothing happens. The phone has been erased, but it is still protected by the passcode.

Can the iPhone be accessible to the thief, can it be easily used by the thief?

No and no

Can the iPhone easily be tracked using IMEI?

No. Apple does not use the IMEI to track or locate a phone.

If phone is activated and connected to internet then you can see the location of the device by using find my