Here are the list of Formula 1 longest-serving team principal/boss/general manager reigns in Formula 1 history to date:
1. Sir Frank Williams and Williams (January 1977 until September 2020)
2. Ken Tyrrell and Tyrrell (January 1968 until December 1998)
3. Ron Dennis and McLaren (September 1980 until April 2009)
4. Christian Horner and Red Bull Racing (January 2005 until present)
5. Franz Tost and Scuderia Toro Rosso later Scuderia AlphaTauri (January 2006 until present)
6. Jean Todt and Scuderia Ferrari (July 1993 until December 2007)
7. Peter Sauber and Sauber (January 1993 until December 2005 & January 2010 until May 2012)
Any additions? Correct me if i wrong!