World Athletics announced that a marathon race walk featuring 25 teams, each comprising one male and one female athlete, will complete the marathon distance (42.195km) in four legs of approximately equal distance, at next year’s Olympic Games in Paris.
Each athlete will complete two legs of just over 10km each, alternating male, female, male, female. According to World Athletics, the marathon distance was selected because of its existing popularity in athletics and its link to the traditions of the Olympic Games.
World Athletics CEO Jon Ridgeon said: “We’re excited to have another mixed relay on the Olympic programme to showcase the skills of both our female and male athletes in one event.” 
“We believe it will be easily understood by fans, will feature exciting competition and, importantly, it will ensure full gender equality across the Olympic track and field programme for the first time.”
https://twitter.com/WorldAthletics/status/1644626361040896000?s=20
Race walking started as a high-society pastime in the Victorian era before debuting as a standalone sport at the Olympics in 1908. The women’s category was only introduced at the 1992 Barcelona Olympics in the form of a 10km event and was later upgraded to a 20km event at the 2000 Sydney Olympics.
Prior to the announcement of the new event, the men’s 50km race walk event was the only event in the Olympic Games with no approximate equivalent for women. This contributed to the Olympic committee’s decision to remove the men’s 50km event and introduce the marathon race walk mixed relay event.
The marathon race walk mixed relay event will take place at 7.30 am on 7 August 2024 at the foot of the Eiffel Tower in central Paris, the same course as the individual race walking events.
The team qualification pathway for this new event is yet to be released.