We have the official announcement of the film That Time I Got Reincarnated as a Slime ( Tensei Shitara Slime Datta Ken ). According to the first information on the official website , the film arrives in autumn 2022.
Check out the teaser:
劇場版制作決定!
2022年秋公開!!スライム旋風は止まらない! https://t.co/XD9FeyH3rJ
杉P #転スラ #tensura pic.twitter.com/yd4VYYoH95
— 【公式】アニメ『転生したらスライムだった件』 (@ten_sura_anime) September 21, 2021
Plus, we have a new image for the film:

Series synopsis:
Lonely 37-year-old Satoru Mikami is stuck in a dead-end job, unhappy with his mundane life, but after dying at the hands of a thief, he awakens to a new beginning in a fantasy realm...as a slime monster( sludge)! As he gets used to his new existence, his exploits with the other monsters trigger a chain of events that will change his new world forever!
Finally, the work received an anime in 2020 by studio 8bit, followed by the second season in 2021.