In-X subnetworks are expected to be located at the very edge of the 6G ‘network of networks’ and provide localized wireless connectivity for in-vehicle, in-robot, in-body communication. By nature in-X subnetworks can lead to dense crowds, calling for efficient radio resource management techniques. In this article, we introduce a hybrid radio resource management framework where the decision capabilities can either happen at a global agent operating on an umbrella 6G network, or locally at each subnetwork, depending on the quality of the backhaul link, the crowd density and the local spectrum sensing capabilities. We present a possible application of the proposed framework for the problem of radio channel selection in a dense crowd. Possible research directions leveraging the proposed framework are also described.