How should a growing organization transition from a single AWS account setup to a proper multi account structure as their AWS usage matures?

A growing organization typically starts with AWS Organizations to create a management account and separate member accounts for different environments or business units, migrating existing workloads gradually into appropriately separated accounts such as production, development, and shared services, while establishing centralized security, logging, and billing practices across the entire organization, rather than continuing to run every workload within a single account where isolation and blast radius control become increasingly difficult to manage.

aws organizations create-organization --feature-set ALL