- She ruled for 30% of the time since the American Revolution
- She oversaw the largest reduction of landholdings of any empire in the history of the world. Notable because it was also one of the most peaceful transitions in history -- Australia, Canada, South Africa, Israel, Egypt, etc.
- She oversaw the loss of Sterling the world reserve currency and the rise of another (the USD, EU).
Notably, without loosing their royal power over those landholdings.
She didn't lose her royal power when handing over those landholdings, nor did she loose it (militarily) to prevent those reductions in the first place.
Seems like she handled it well.
There was little for the Royal Family to adjust to.
They were the sovereigns of those nations, if independent from the UK. They still "appoint" the PMs of those countries and have a fair amount of political influence via governors.