With Lucifer having a cameo during the recent Crisis On Infinite Earths event in the DC Arrowverse, you may be forgiven if you thought his comic was doing well. But, as it stands, DC Comics has presently decided to cancel Lucifer as of March 2020’s Lucifer #18.
The following is sourced from https://www.cbr.com/dc-lucifer-remaining-issues-canceled-straight-to-collected-edition-sandman-universe/amp
With the cancellation of Lucifer, its remaining issues (#19 to #24) will be gathered together, and released as an Original Graphic Novel (OGN) to end the series run. According to news first broken by Newsarama (and represented in the source article linked above from CBR), the final arc (written by Dan Watters with art by Sebastian Fiumara) will not be affected by the shift from single issues to release as an Original Graphic Novel (OGN).
This OGN will supposedly overlap with the next planned Lucifer TPB, Volume 3 The Wild Hunt, as that volume is supposed to contain issues #14-#19. As for the release date of the final OGN, collecting issues #19-#24, there is no set release date yet according to the Newsarama info as reported on by CBR.
While we cannot find info on said trade, we can take a glimpse into what was once coming by simply going to look at the pre-COVID-19 solicits and pre-orders to see what was announced. So, with that said, looking up the topic in question shows that we have info on issues #19 to #21 in pre-order that we can examine content wise.
The following info is sourced from https://www.tfaw.com/catalogsearch/result/?q=Lucifer
Lucifer #19 – ‘The Wild Hunt’ reaches it’s stunning conclusion as the Prince of Darkness travels to the necropolis known as Litharge (from the Sandman: Worlds End) to wage war against Odin’s hunters.
Lucifer #20 – At last, the devil goes to hell.
Lucifer #21 – Lucifer trespasses into the garden of Destiny of the Endless, but for what nefarious purpose? Nothing less than tearing a page from the Book of Destiny itself.
Presently the most recent pre-order past The Wild Hunt is the second Omnibus. Solicited for October 28th 2020, the title solicits read as thus.
“In the concluding omnibus collection, Lucifer Morningstar has resigned his throne and abandoned his kingdom, and filled his days running Lux, Los Angeles’s most elite piano bar. After agreeing to complete a task assigned by the Creator Himself, Lucifer’s retirement has become a thing of the past. The Lord of Hell must team up with unexpected allies in order to not only fulfill the task sent by the Creator, but to stop the universes from collapsing and destroying all creation. The Devil’s hands have been idle long enough. Collects Lucifer #36-#75.”
As of this post there is no news as to when the final Lucifer OGN will publish.