Calibrated backscatter intensity largely ranges between 0 an 1, but artificial surfaces and volumes can have extremely high values beyond that. This is usually tackled by converting the data into dB scale. This shifts the maxima towards the mean and stretches the dark areas with little contrast.
Please have a look here: Classification Sentinel-1 problems with MaxVer
Maybe also helpful: Page 9 and 10 (especially Figure 11) of this tutorial: Synergetic use of S1 (SAR) and S2 (optical) data and use of analysis tools