It has already been confirmed by Warner Bros Japan and the production team responsible for the anime that Danmachi will receive its 4th season.
The new season of the anime will air in Japan in 2022, although the exact month of the premiere has not yet been confirmed.
In addition, a trailer for the anime's 3rd OVA was also released.
The 3rd season of Danmachi aired on October 2nd, 2020. It's worth remembering that the premiere was originally scheduled for an earlier date, but it had to be postponed due to the pandemic.
Source: ANN