Yes, DJI Mic transmitters support standalone recording. Press the recording button on the side of the transmitters. Solid red light indicates that recording has started. When fully charged, it can record for up to 5.5 hours. With a constant power supply, it can record up to 14 hours of 24 bit lossless audio.
Note: Audio will be saved as one file for every 30 minutes during standalone recording. When internal storage space runs out, new audio will replace the earliest ones, and new files will also be saved every 30 minutes.