Ask people all the time for feedback. Make your asks specific, and your tone curious so it's safe for the other person to tell something critical. People know when you're just fishing for compliments. Examples (thread)
After a presentation you gave: "How well did you think my points landed? What would have made them clearer?"
After an analysis you completed: "How impactful was this to your team? What would have made it more useful?"
After a project with another colleague: "If we were to do this project over again, what would we do differently and what would we do absolutely the same?"
You can also ask in an open-ended manner via an e-mail--"I'm looking to improve and be a better colleague. Help me understand my strengths and areas of growth. What do you think I do really well? What could I change to have more impact?”
For a general fool-proof template: "How could this have gone twice as well?"
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