Sometimes you can help people grow a lot by getting out of their way! It’s amazing how people often step up to take on more responsibility when they’re needed (see how many CEA, 80k, and EV staff grew when they had to step up post-FTX).
Give them big ambitious targets that you’re not sure they’ll be able to achieve. Support them and make sure it’s not catastrophic (either practically or emotionally) if they fail.
Look for things that are a stretch but not impossible
Look for things that lean into their strengths
Really give them responsibility for the areas that they’re owning. Set context, rather than controlling.
Do:
You can (and should) coach them
You should stay synced up with them on what their goals are, which goals are most important, metrics for success, etc. (writing is the best way to keep this transparent)
If things don’t go well, you can change their responsibilities such that they no longer own the area (or are fired or whatever)
Give them feedback about how you think things are going, and your overall assessment of their performance
You can even share input as long as you’re very clear that they can ignore you
Don’t
Do their job!
Hand down decisions
Insist on co-creating plans for hitting their goals
Meddle with them doing their job!
For senior staff who you trust, you should also try to get them involved and feeling responsible for running the organization with you: set up leadership team meetings such that you’re discussing the biggest issues together, and taking some collective responsibility for making things great (though the buck stops with you). If you can create a leadership team that’s working together to run the organization, that’s the best step you can take towards making yourself replaceable, and it’s probably better than having a single talented successor with a weak leadership team.