I am currently working on the same phones, Poly CCX, and Microsoft Teams. The Poly CCX firmware released recently, version 1.0.1.0054, will make the Poly CCX (400, 500, and 600) honor the port configurations you set in the Teams Admin Center under Meetings, Meeting Settings, in the Network section. The suggested setting is TCP/UDP ports 50000 - 50019 for Audio, 50020 - 50039 for Video, and 50040 - 50059 for Screen Sharing.
Using the packet capture feature, we saw voice traffic from the CCX using the configured ports for Audio but not automatically adding DSCP value. If you can use source ports in your Quality of Service settings on the switch, you can then set a rule to mark TCP and a rule for UDP for the selected ports with the appropriate value.
Microsoft's document for setting up QoS in Teams was updated recently, 8/6/2020. It explains configuring the ports and recommendations to insert DSCP markers.
https://docs.microsoft.com/en-US/microsoftteams/qos-in-teams?WT.mc_id=TeamsAdminCenterCSH
Good luck