Some examples of good selling points in a cover letter are:
1. “In 2021 I was able to help my company achieve [something]...”
2. “I was awarded [X] in 2021 due to my exceptional work in [Y]...”
3. “I built [X] team out from scratch to help [company]...”
4. “I am currently in the top 1% in [Y]...”
5. “I have managed large scale projects when it comes to [X]...”