I only have experience with Dosbox 0.72, but here goes. Set your fullresolution to something 4:3 such as "1440x1080" or "original" and let your display stretch it.

Works like a charm.. there are very minimal black bars on the edges, its a shame i can't easily resize my screeen with front controls but it looks better.. now for some classic dos gaming 🤣 its gr8 laughing at those old text based adventures...

Why do you want your DOS games distorted?

Setting it to original works for an entire full screen stretch(640x480), however, it is blurry and not as clear as running 1920x1080 and having a stretch.
When I run 1920x1080 is looks so good but has the horizontal black area on the left and right.
There has got to be a way to leave it set to 1920x1080 without having those bank areas on the sides. I tried messing with aspect and scaler, but the best I can do is with the black bars. Setting fullresolution to original does what I want at the expense of clerity.
Also, the direct3d output, is that currently supported on 0.72? or do you need those patches for it? Because when I tried it, it shrank everything.
And also SVGA? is that supported or needs a patch as well?

Direct3D is not supported, so choose any other OUTPUT except for surface or download an unofficial DOSBox build with Direct3D support.

SVGA support is internal to DOSBox, it's not an OUTPUT option and yes SVGA is supported in DOSBox.

The following are incorrect:
aspect=16:9
scaler=hardware3x

Making up your own config options doesn't help with anything.

I don't use those options, it is in the first posts config. I was just curious.

Here is what I been using to exclude setting fullresolution to original:
fullscreen=true
fulldouble=true
fullresolution=1920x1080
windowresolution=1280x960
output=ddraw

aspect=false
scaler=normal2x

here si the best confinguration I could do on my 1920x1080 LCD TV.

fullscreen=true
fulldouble=true
fullresolution=1280x960
windowresolution=1280x960
output=ddraw

aspect=true
scaler=normal2x

it allows complete fullscreen and minimal blur/stretch effect from the original 640x480.

What I can't figure out still is why 1920x1080 just doesn't work perfect.
Why the black bars on the side.

What I can't figure out still is why 1920x1080 just doesn't work perfect.
Why the black bars on the side.

Dosbox adds them to keep the aspect ratio of the game correct. Games are 4:3, so the only way to not distort them on a widescreen display is to either crop off the top and bottom of the image (not done by dosbox) or add black bars to the sides (done by dosbox). If you want your games very sharp looking, try output=openglnb. Fullresolution=1440x1080 might also work for your display.

I tried 1440x1080, but it didn't work. sharper as expected. switching aspect ture/false just made side bars or center with black border all around.
can't tell if the openglnb helped, but it seemed to look really good.
What is the openglnb vs opengl?

Still makes no sence to me that I can stretch 640x480 to my TV perfect but cant stretch the 1920x1080, or the 1440x1080.
Normal2x did a good job with 640x480 and 1280x960.

Also i don't mind the stretched look.... I am going for clarity. 640x480 stretched vs 280x960 stretch is a big clarity diffrence. Alot sharper looking.

agree with ripa, openglnb has always given me the best results.