For anyone who is interested, here a Python 3 script that stops or starts all map services in the ROOT folder. It can be started with the following command:
"<arcgis install dir>\ArcGIS\Server\framework\runtime\ArcGIS\bin\Python\envs\arcgispro-py3\python.exe" <file location>\Start_stop_arcgis_services_in_folder_https_P3.py %1 %USER% %2 %PASS% %3 %SERV% %4 %MAP% %5 %STARTSTOP%
Any improvements are welcome of course