Does an Avantree LE Audio transmitter work with my Sony WH-1000XM5 or WH-1000XM6?

Yes.

• Auracast broadcasting: Both models work with Avantree 
  C82 Aura, Audikast 4, DG60 Aura, and Voyager series transmitters.

• LE Audio unicast (point-to-point): They work with the Avantree C82 LEA transmitter.

Note: The WH-1000XM5 requires the latest firmware update (V2.4.1 or later) to enable LE Audio / Auracast.