3GPP 38.300 v19.3.0 — the document's own text
5.2.6 Downlink Reference Signals and Measurements for Positioning
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).
The DL Positioning Reference Signals (DL PRS) are defined to facilitate support of different positioning methods such as DL-TDOA, DL-AoD, multi-RTT through the following set of UE measurements DL RSTD, DL PRS-RSRP/DL PRS-RSRPP, and UE Rx-Tx time difference respectively as described in TS 38.305 [42]. The DL PRS also facilitates Carrier Phase Positioning measurements such as DL-RSCP and DL-RSCPD as described in TS 38.305 [42].
Besides DL PRS signals, UE can use SSB and CSI-RS for RRM (RSRP and RSRQ) measurements for E-CID type of positioning.