Here are the highest viewership numbers for specific edition of events/tournaments:
Soccer/Football - FIFA World Cup Final - 3.5 billion viewers for the 2018 final
Cricket - ICC Cricket World Cup Final - 1 billion viewers for the 2011 final
American Football - Super Bowl - 102 million viewers for the 2021 Super Bowl
Basketball - NBA Finals - 31 million viewers for the 1998 Finals
Baseball - World Series - 52 million viewers for the 1986 World Series
Ice Hockey - Winter Olympics Men's Ice Hockey Final - 34.7 million viewers for the 2002 final
Rugby Union - Rugby World Cup Final - 57.9 million viewers for the 2019 final
Tennis - Wimbledon Men's Final - 9.6 million viewers for the 2019 final
Formula One - Monaco Grand Prix - 110 million viewers in 2019
Boxing - Mayweather vs. Pacquiao - 4.6 million pay-per-view buys in 2015.