https://www.techradar.com/news/luigis-mansion-3-release-date

It’s been five long years since Nintendo last released a game in the Luigi’s Mansion series, and with fans beginning to give up hope of another, the news that a sequel will hit Nintendo Switch in 2019 is very welcome news indeed.

Announced with a trailer during a Nintendo Direct on September 13, the tentatively named Luigi’s Mansion 3, is set to be released on Switch at some point in 2019 - so far no official release date has been divulged, but with a remake of the original Luigi’s Mansion coming to 3DS on October 12.