Hello,
on BB-STM32WL, R4 and R5 allow TX active mode selection between 14 and 20 dbm. Default selection is 14 dbm. Is this selection user changeable?
Yes. As you noticed by default 14 DBM is set with R4 not placed and R5 is 0R. To change to 20DBM unsolder the 0R resistor and place it on the R4 position (leaving R5 unconnected). This is visible in "Table 1" the schematic.