The present disclosure discloses operating methods of a user equipment and a base station in a wireless communication system, and a device supporting same. According to an embodiment applicable to the present disclosure, the user equipment may establish connection with the base station, on the basis of a synchronization signal/physical broadcast channel (SS/PBCH) block received from the base station. Subsequently, the user equipment may be configured, by the base station, with a transmission mode in which data generated from the same information is transmitted from a plurality of transmission reception points (TRPs), and may determine a size of a transmission block related to data provided from the plurality of TRPs on the basis of the transmission mode to obtain related data information. Accordingly, the base station and the user equipment can configure/determine the size of the transmission block related to the data without ambiguity therebetween.