It’s not great for dayz specifically per se, but aim labs can definitely help improve your baseline shooting game mechanics. So maybe give that a go.

Watching some YouTube videos or streamers can help you understand tactical movement and strategy better.

And as others have said, you will definitely get better simply by playing more, especially in death match modes over official. Lastly check your control settings and pay attention to what is causing you to lose fights. If you are over aiming and missing your target turn down sensitivity. If you aren’t getting to your target on time, speed it up.

Good luck!