Hi, how can you make sure you have a US model that will meet FCC standard? serial number and model number? when new in box

Look for the ADS-B sticker on the front right arm.

No marking on outside of box.

The box has the marking too.

All of them meet "FCC" standard.  There is no different FCC/CE model, they adjust based upon location. There is only Airsense and no Airsense models (which has nothing to do with the FCC).  It seems the OP's location is in the US, so buy from an authorized US dealer and it won't be an issue.

Hi. Thank you for reaching out to DJI Forum. With regards to this query, as our DJI co pilots advised there are multiple ways to check if the drone is a US model. Please PM me the serial number for me to check it on the DJI database. Thank you.

Currently I'm a Mini pilot but may in time add it's Big little brother to the family. This new to me pleasure sport/actively  to share and experience has been great, sad that it's sharing a World history mark and some are trying to take advantage of our needs.
Wasn't planning on my new family member for a while but ran across deal that seemed to good to be real or true(security precaution in place) but I went ahead and ask seller a few questions like when I started this post was it a USA based (with ADS-S active) and was it registerable to name key ones. This was a new Air 2 (3) with a US based seller not a listed Authorized seller of DJI products. I went ahead and also alerted listing site of my concern but they were all over it going through their procedures for New sellers and the standard of protecting Buyers it does go both ways just to mention.
Story getting to long in short just step up and buy from dealer for new and fill comfortable buying already tested/used drone. So in the end no I didn't get a great deal it's sad because there out there So lets stay safe and keep enjoying our some times small flying zones Ok some have Larger zones we're all trying.
Thanks DJI Paladin for offering in a PM to check SN to see if it was a active ADS-S drone.
Enjoy Air timeNo need to mention site because I didn't.