Yes, there are a few options available for using your IDX battery with a D-Tap connector to power your Canon EOS R5C camera.
One option is to use a third-party DC coupler with a D-Tap connector, such as the IndiPRO Tools D-Tap to Canon LP-E6 Dummy Battery. This device will allow you to connect your IDX battery to your camera via a D-Tap connector, providing power to your camera. However, it’s important to make sure that the voltage and current output of your battery are compatible with your camera, so be sure to check the specifications before using this option.
Another option is to use a D-Tap to DC coupler converter cable, such as the Andycine D-Tap to DC Cable. This cable has a D-Tap connector on one end and a 5.5mm x 2.5mm DC connector on the other end, which can be used to connect to your Canon DC Adaptor DR-E6C. This will allow you to power your EOS R5C camera using your IDX battery with a D-Tap connector.
I hope this helps! Let me know if you have any more questions.