n other words RSRP (Reference Signal Receive Power) is the average power of Resource Elements (RE) that carry cell specific Reference Signals (RS) over the entire bandwidth, so RSRP is only measured in the symbols carrying RS.
RSRP is the average received power of a single RS resource element.
UE measures the power of multiple resource elements used to transfer the reference signal but then takes an average of them rather than summing them.
Reporting range -44…-140 dBm