A method and a User Equipment (UE) for beam operations are provided. The method includes monitoring at least one of a plurality of Control Resource Sets (CORESETs) configured for the UE within an active Bandwidth Part (BWP) of a serving cell in a time slot; and applying a first Quasi Co-Location (QCL) assumption of a first CORESET of a set of one or more of the monitored at least one of the plurality of CORESETs to receive a Downlink (DL) Reference Signal (RS), wherein the first CORESET is associated with a monitored search space configured with a lowest CORESET Identity (ID) among the set of one or more of the monitored at least one of the plurality of CORESETs.