This sound effect can be found on Foley Sound Library, which was made by The Hollywood Edge. It's the same sound effect as Body Falls Racket Bal PE106601 and Foot Stomps Hard Rctb PE124201, both from The Premiere Edition Volume 1. It shouldn't be confused with Anime Body Fall Sound 1.
Sound Effect Description
Heavy Body Falls With Reverb; Heavy Body Fall With Slap On Surface And Lots Of Reverb. - Fight Impacts