Embodiments herein relate to a method performed by a first network node for enabling at least one second network node to perform a transmission in a wireless communications network. The first network node and the at least one second network node performs transmissions using contention-based transmission resources of the same frequency. The first network node determines an indication of a maximum transmit power for the transmission by the at least one second network node to be used by the at least one second network node when the contention-based transmission resources of the same frequency is available for transmissions by the first network node in the wireless communications network. Then, the network node transmits the determined indication of a maximum transmit power to the at least one second network node. Embodiments of the first network node are also described.