Man, original DS games look terrible on the 3DS, is there anything I can install that will fix this?
Actually take a look at this thread I found: https://gbatemp.net/threads/twpatch-lets-you-use-custom-ds-i-mode-scaling-filters-on-your-3ds.543291/
Might help you
I was going to bring up TWPatch myself, too. @Dirt_Owl@hexbear.net I will warn you that while you can see previews of the different filters, applying one takes a long-ass time, I'm talking multiple minutes, so choose wisely.
The ability to boot a DS game in its native resolution is done by holding START or SELECT while it boots up. It's actually part of the official firmware, not something added by homebrew software:
Show
You can also just hold select while booting up a DS game and it won't scale at all, but then you get very large black borders
you can install that dog game, nintendogs. Cool game. You should play it.
What's nice is that you can scratch your ds with a stylus to transmit scritches to the cute doggerinos on the screen. It's a neat feature because it is cool
I think there is a setting in citra to render at a native resolution. But then the games look tiny with a huuuge gap between the screens. That's why I've got a DSi XL from Japan. They are really cheap and easy to mod, while giving me a native resolution big screen.
EDIT: Oops, not citra. The homebrew BIOS, I forgot it's name. Luma something?