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Unsure what you would consider "internal". You've already mentioned WRED, which some Cisco devices QoS features can utilize any DSCP marking for a different drop treatment (within the same queue). Some Cisco devices (switches) support multiple (settable) drop limits, WTD, for DSCP marked packets or WRED.
BTW, to be a little more precise, on Cisco routers that I've used, generally, by default, all interfaces only have a single FIFO queue with a single default tail drop except for "slow" serial interfaces which default to WFQ. Different drop treatments, require activation of interface WRED or WRED within a CBWFQ class. Once activated defaults will drop DSCP marked packets differently.
On Cisco QoS capable switches, their default tends to be no QoS, another instance of a single FIFO queue with tail drop. On those, activation of QoS often also defaults to different drop treatments if using DSCP markings.
