How can I check IMEI status for iPhone 14 Pro Max?

Ask the carrier.....or.....check on the iPhone

Settings > General > About > Carrier Lock

If you don't know who the carrier is, or the phone is not yours......you can be pretty certain that the phone is locked to the carrier and possibly blacklisted

Read this before purchasing a used phone -

The All Too Common SAD Reality of Buying a Used Phone - Apple Community