3GPP 38.300 v19.3.0 — the document's own text
5.7.4.2 Power Control
Taught in 2. The six working groups and the line between them (TSG RAN — the group that specifies the radio, overview), 2. The six groups, and what each one worries about (TSG RAN — the group that specifies the radio, quick start).
For in-coverage operation, the power spectral density of the sidelink transmissions can be adjusted based on the pathloss from the gNB.
For unicast, the power spectral density of some sidelink transmissions can be adjusted based on the pathloss between the two communicating UEs.