Theoretically: Yes, but probably not in the way you're thinking.
Most of the sorts of things that humans think of as traits are not the immediate result of things your DNA is doing right now, they are the result of structures whose form and function are the result of things your DNA was doing a long time ago. Your eyes work the way they do because of the cells that make them up and the ways those cells are attached to one another, even if you did replace some of the DNA sequences in those cells with hawk DNA they wouldn't suddenly start working better. The most likely outcomes of that would be that your eyes simply stop working as your cells either stop making things that they need or start making things which break the existing machines or that nothing changes at all.
Now, there are a few things that might theoretically be moddable into living organisms this way if you waive the massive computing power that would be needed to actually find the useful ones(preferably in a way which doesn't involve risking poisoning yourself), but most of them aren't that exciting. They're the sorts of things that happen at the cellular level that you usually don't even notice. For example, you could add some chlorophyll producing DNA into someone's cells and over the course of a few months or years they could gain the ability to eat slightly less if they spent a significant amount of their day sitting in the sun. Or they could absorb a protein which works like fibrin but a bit more efficiently, so their wounds scab over a bit more quickly. Maybe if they're lucky(I'm not sure if these exist in nature) they could find more efficient versions of the energy converting structures used by their cells to gain a bit more endurance off of their body's fat and sugar reserves. With the right proteins they could become more resistant to cold temperatures or make their skin glow slightly if they wanted to. I recall reading at one point about an organism with a protein that repaired the "junk DNA" on the ends of the strands, thereby preventing aging, which is probably the most exciting item on the list. Keep in mind, if you go down this path that the changes will take a while to kick in, the cells need time to actually produce the required proteins and for those proteins to reach useful levels in the body.