I hope getting a 7 seater is worth losing 20k from what you paid. The best way to sell IMO is listing on craigslist, facebook marketplace, and see if you get feelers. If not then start expanding your exposure with pay for list sites like autotrader, cars.com, etc. From there if you get zero bites reach out to carvana, vroom, etc but they will offer you probably 20-25k below MSRP pricing.
Define "best". Getting the most money may involve tradeoffs in safety and convenience.
Craigslist and Facebook Marketplace could get you the best dollar return, but can be pretty risky. Lots of scammers out there, and could expose you to physical danger from someone trying to rob you of your car.
CarMax, Carvana, Vroom, etc. are safer. Trading in is also an option. It will involve some research to figure out the best tradeoff.