By release date: Resident Evil on 15 March 2002, Apocalypse on 10 September 2004, Extinction on 21 September 2007, Afterlife on 10 September 2010, Retribution on 14 September 2012, The Final Chapter on 23 December 2016 (Japan; the US followed in January 2017), Welcome to Raccoon City on 24 November 2021, and Resident Evil on 18 September 2026.
The first six are one story. Each is a direct sequel to the one before, and all follow Alice, so they are best watched in release order.
Welcome to Raccoon City is not connected to them. It starts over from the first two games, with Claire and Chris Redfield, Jill Valentine and Leon S. Kennedy in 1998.
Zach Cregger’s 2026 film is a second reboot and stands alone as well: it needs neither the Anderson films nor the 2021 one.