So to answer your question, no other artist ever swept all daesangs at a korean award show outside of BTS.
Now, yes they done it other times many times. First they also swept all daesangs at MAMA in 2019 and they kept sweeping it for a total of three years in a row. (2019, 2020 and 2021). MAMA even creating a special platinum award for artists that sweep all daesangs in a year in 2022 and no one got it since BTS.
Usually it's pretty hard for one group to sweep all awards because of how k-pop works. You probably know how girl groups have more popularity with the GP, and so can more easily have big/viral hits, so most of the time it's a gg winning Song of the Year.
But on the other hand, boy groups have stronger/more dedicated fanbases so they are overall selling more albums than ggs. And as the Album of The Year award is mostly about album sales, it's almost always a boy group that takes it.
So just with that it's hard for either a boy group or a girl group to take all daesangs.