I am looking at two Baritone Acoustic Guitars. One has a 26.8 inch scale and the other is a 28 inch scale.

These are expensive guitars so what exactly are the differences that will come with these two lengths? I've read that the shorter scale may have better mids while the longer scale may have better bass but I'd love as much detail as possible in regards to tone, playability, tuning, and whatever else.

I plan on playing in C tuning.
Longer scale lengths require more string tension to bring up to pitch.

They also would require greater stretches to produce chords shapes you can do easily on a standard 6 string, (25.5" scale max).

Basses have long scale but as often as not, you're playing single notes, so the whole hand moves, mitigating the effect of the long, (about 30"), scale.

Either of the guitars you mention should tune to C.

"Baritone guitars" are also called "D scale guitars", one has to assume in the same way you can tune down an "E scale guitar" to D-d with many bad side effects, the same deal should attach going from D-d to C-c.

In fact, many 12 string users tune to C#-c#, with 25.5" scales, just by upping the string set to "medium 12 string", about .12 to .052. It work because there's a ton of tension with those string sets. (Not quite a "ton" but over 300 Lbs).

As far as overall tonality is concerned, with acoustics that going to depend on the quality of the top, the bracing strategy, as well as the back & side woods, likely more so than the scale length.

In the end, if there's a lot of money involved in the purchase, it's almost mandatory that you audition the guitars.

Other than the intrinsic sound of the guitar, toying with string gauges and alloys on the same instrument, can tweak the sound to what you'd like it to be.

It would be better if you post the make and model of the guitars in question, perhaps someone has direct experience. But, their sense of hearing may differ from yours.... so caveat emptor anyway.