Is GTA IV available on Xbox One format?

The intersecting sagas of Niko Bellic, Johnny Klebitz and Luis Lopez in grand larceny Auto IV and grand larceny Auto: Episodes from Liberty City, are now all playable on Xbox One via Backward Compatibility. All versions of the sport , including grand larceny Auto IV: the entire Edition, are compatible on Xbox One.

The intersecting sagas of Niko Bellic, Johnny Klebitz and Luis Lopez in Grand Theft Auto IV and Grand Theft Auto: Episodes from Liberty City, are now all playable on Xbox One via Backward Compatibility. All versions of the game, including Grand Theft Auto IV: The Complete Edition, are compatible on Xbox One.

Yes you can go on the store

Technically it's the Xbox 360 version that's backward compatible, but it is playable on the Xbox One. And it's available digitally.

if you put this question on the search bar it might tell you

It’s not a available for download. 

Yes it is. At least the physical version. No idea about the digital version since I haven’t checked the xbl in a long time.