At many companies now, the requirement to be promoted from Manager to Senior Manager is having X number of managers under you. This is frequently done by splitting the responsibilities of your current team into multiple teams. A great way to accelerate that is to have one of your ICs with context and rapport transition into managing one of the sub teams.
There's also the slightly more twisted version of this, where companies have special 'leadership' training programs and the employees on teams get 'hand picked' by their managers or the org. It tends to lead to lead to knock-on effects like managers selecting for sycophants in hiring, the program being used as an additional carrot/stick (I saw one abusive manager threaten to get someone 'knocked out' of the program I'm thinking of,) as well as generally causing a level of artificial false seniority.
