Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a relay user equipment (UE) may transmit an aperiodic channel state information (CSI) request to a UE, wherein the aperiodic CSI request is for sidelink communications; receive, from a base station, an indication of one or more modulation and coding schemes (MCSs) for sidelink communications between the relay UE and the UE based at least in part on transmitting the aperiodic CSI request; receive, from the base station, a communication to be relayed to the UE; and relay the communication to the UE via a sidelink communication that is modulated using an MCS of the one or more MCSs. Numerous other aspects are provided.