You can operate reverse loops manually or automatically using DCC. You must double gap (completely isolate) both ends of the reversing section.
If you choose manual operation you will power the reverse section separately and use a switch or relay to handle the polarity change as the locomotive enters and leaves the reversing section.
If you use an auto reversing strategy you will power the reverse section separately and use an auto reversing booster or other auto reversing device to handle the polarity change.
Note that when the polarity change occurs DCC equipped locomotives will continue at the speed and in the direction commanded but any analog engines running will reverse direction because they "see" the polarity change and respond to it.
If you choose the auto reversing booster strategy, you will need at least two boosters. One will be the system reference booster and the second will be the auto reverser. The good news is that you can run more than one reversing section on a single auto-reversing booster.
Note that some auto reversing devices require that you make changes to locomotive wiring where the pickups are not "side by side" on the locomotive. This is an issue in many steam locomotives where one power pickup is on the locomotive and the other is on the tender.
Adapted from "Digital Command Control: The Wave of the Future", by Zana and A.J. Ireland.