[Phanx]

That image doesn't appear scaled down, so OP is just playing on a tiny monitor; I'd guess it's a laptop. Not much room to scale anything down, especially if OP also has poor vision like me.

However, even though everything is fairly large, it's still hard (for me) to read. Try to find a more readable font -- eg. one that has more standard letter shapes (not "cool" scifi/futuristic shapes) and isn't so bold. Then try to increase the contrast between the text and the background it's on -- your target frame is quite readable, but your raid frames are pretty unreadable. You don't need both the text and the background to be brightly class-colored. Personally, I'd leave the text color as-is, and make the background much darker.

You're also wasting a lot of space on buffs on the target frame. Most of those buffs aren't relevant to your gameplay, and there's no way you have time mid-combat to scan 40 small buff icons to see if a particular buff is up. Same goes for debuffs on hostile targets, and the buff icons on the player frame. If your unit frame addon can't filter auras, just turn off its aura display, and get a dedicated aura addon that can filter all the irrelevant stuff out, so you only see the buffs and debuffs that are immediately important to you.

I'd get rid of the second chat frame, and use tabs instead. There's no reason to see general chat with a bunch of LFG spam while you're already in an instance. This will free up a lot of space.

Consider hiding your damage/healing/absorb meter in combat. It can be a useful tool to help assess performance after the fact, but you shouldn't be "playing to the meter" and focusing on it in combat.

You currently have three separate lists of boss timers. I'm not sure why your boss mod is doing that, but you should only have one list, or maybe two if you're setting it to show "soon" timers separately, in which case the "later" timers can be shrunk down and moved down to a corner, since they'll move to the center when they're close to expiring.

Your action buttons are taking up a lot more space than they need to be. Move them closer together to give yourself more space. You could even make them bigger, and still have more space.

The heavy black borders around everything look really clunky, especially since they aren't even the same heavy black borders. Try shrinking it down, using a different lighter/thinner border, or at least making them all match.

Finally, I find your lack of alignment disturbing. Anything near the bottom of the screen, for example, should be the same distance from the bottom of the screen as anything else, and things should be the same distance from the left side of the screen as they are from the right side of the screen. Check out the horizontal spacing on the outsides of your chat boxes for an example of that, and note how your chat frames are closer to the bottom of the screen than to the sides.

Oh, and you may want to turn off player names in the game world. They add a lot of clutter, and are generally not very useful in PVE since you're not clicking on players in the game world to target them; in your screenshot, they're not even big enough to read.