3CX does pass the "From : Display Name" over to Teams, so assuming your SIP Trunk Provider sends something in this SIP field as a CNAM, then it should be passed onto Teams.
You can verify what is being received by your SIP Trunk provider and then being passed onto Teams from the Management Console --> Activity Log. Before you check there though make sure to set the logging level to Verbose from the "Settings" option that is there.
Make and inbound call, answer it from the Teams client, then go there and filter with the last Call ID, that would be the easiest way (don't forget to use the "Load More" button to see all logs...).