Good architecture can respond to new requirements. It’s malleable where it needs to be.
A good leader trusts their team. And builds their team so they can trust them.
Architecture leads software, it defines the agility of the rest of the development, and it defines the fixed points that cannot be changed, that will always tend back to the initial conditions.
Get the architecture right. Decide as a team, and document the decisions as you go. Sometimes a decision is made on a proposition that is false. Sometimes the best solution yesterday is no longer the best solution today.
Everyone should be designing architecture of the system, and everyone should be reviewing it (pull requests on the written decision are great for capturing the discussion).
Your job as a leader is to make sure those discussions happen and are productive. Put the architecture decisions and the associated documentation next to the code, so they are as open for extensions and available for refactoring.
Democratise the architecture – get everyone to buy in, and you won’t come back to the project in 5 years and wonder when the monsters and hurricanes attacked.