How to readout current PID values on Ender 3

Run

M503

which will show all EEPROM configuration values, among them these lines:

M301 P29.34 I3.58 D60.08
M304 P427.57 I84.18 D542.91

Note that the M301 line represents the Hotend PID values whereas M304 represent the Bed PID values.