Does this solid line in this situation indicate a place to stop because of the "stop" sign?

Beyond sign B-20 "STOP" there is a thick, solid transverse line on the roadway. This is the mandatory stop line P-12, and it is exactly this line that marks the place where you must stop because of the STOP sign. You stop so that the whole car is before the line - the front of the car must not go onto it.

The Regulation on road signs and signals says directly that sign P-12 shows the place where a vehicle stops because of sign B-20 (and also B-32). With the STOP sign, stopping is compulsory even when nothing is coming, and when the line is painted, you stop exactly before it, not further on, at a place with a better view.

Legal basis: § 21 para. 2 and § 89 para. 1 of the Regulation on road signs and signals