Elseworlds was a DC Comics publishing imprint started in 1989 that presented stories set outside the DC Universe's main continuity.

Source: https://collider.com/what-is-elseworlds-dcu/

Fans can expect sequels to popular series like Dark Knights of Steel and DC vs. Vampires in the upcoming Elseworlds releases.

Source: https://screenrant.com/dc-elseworlds-series-batman-barbarian-nightfire-nycc-2023/

Gunn discussed DC Studios' ambitions for a future DC universe that will convey "one story" across film, "television, gaming, and animation," while also intending to release movies and TV shows outside the main DC universe under the label "Elseworlds."

Source: https://www.cbr.com/titans-bryan-edward-hill-celebrate-james-gunn-dcu/

However, they will be referred to as Elseworlds.

Source: https://www.cbr.com/james-gunn-dcu-chapter-1-gods-and-monsters/

This extends to various Elseworlds and alternate continuity stories, most of which relegate the Last Martian to a plot device or cannon fodder.

Source: https://www.cbr.com/martian-manhunter-status-quo-powerful-dc/

Those movies, along with “Folie à Deux,” belong to their own universe called DC: Elseworlds, which means they are not beholden to Gunn and Safran’s vision for the future of DC.

Source: https://www.columbian.com/news/2023/apr/09/everything-to-know-so-far-about-joker-sequel/