I agree with the sibling, but let me be more explicit: It's going to be hard to take time off, "level up" and then come back and get another job. Your best bet is to stay where you are and keep your job. The company has already invested in you and your manager has every incentive to help you improve rather than finding someone else.

You should go to you manager with a look to the future: come with some specific things you can do differently on the next project, and perhaps also some general 'goals' for improving your skill.

Then, most importantly, do what you said, and get better.

All this assumes you are happy and want to stay in engineering, if you do think you'll be happier doing something else, then by all means go ahead and do that.