Hi Mega Shocked, a Happy 2021 also to you too!

Mega Shocked (./141):
Art of Fighting 2 has a crazy intro that scales the sprites and backgrounds 4x and displays the images in 4 quadrants on the same screen!

I think this is just a neat trick - I guess these are four pre-rendered screenshots which are scaled down and not real game scenes (this would exceed the 96 sprites per scanline limit).

Mega Shocked (./141):
I guess what I'm confused about is... does a Scroller (Background GFX) taking a typical 21 sprites need to be split in half to take up 42 sprites just to ensure the seam issue that happens on the 14th or 15th sprite can be hidden during scaling or is there a flag that can be set to allow the original 21 sprite scroller to be scaled freely taking far less sprites and effort to mask the seam?

The seam issue only happens when scaling vertically (at the 16th "pixel line" of the 16th tile), you only need to take this into account If your backgound height is bigger than 16 tiles (256 pixels).
As Blastar wrote the maximal horizontal scaling size is 32 tiles (512 pixels).