Andy Grove talks about this in his excellent High Output Management, where he asks the question: how should knowledge managers (senior ICs) and people managers spend their time?

His answer is: on high leverage activities. Instead of fixing a small bug that affects a few customers, fix a big one that impacts revenue; train others to be better engineers, multiplying their future output; improve the process your team uses to build product. Essentially, look for activities that multiply output, rather than add to it.

They multiply the skills of the people around them. They make everyone else better. It can be via a tool, a process, good code review, opening a path of knowledge, being supportive, giving confidence, listening well, or any number of other things.

Gandalf in the battle of Minas Tirith is a huge force multiplier. He embiggens the courage of everyone near him and makes them fight harder and better.

Someone who leads, inspires, gets people working at their best.