I’ve found one of the best things I can do to help my jr devs feel more confident (and be willing to ask for help) is highlight my screwups and “basic” things I’ve just learned. It make me seem more approachable and less like everything I say is a pronouncement from on high, it makes them more willing to admit to their own mistakes, it clarifies that we’re all learning stuff all the time and it helps spread knowledge about things that folks might otherwise be too afraid to ask about for fear of looking silly.
A benefit of being a sr dev is getting the benefit of the doubt on mistakes, so I might as well use that to my advantage and let everyone learn from them, not just me.