Borrow, don't buy whole.
The Scaled Agile Framework (SAFe), created by Dean Leffingwell in 2011, is the most widely adopted scaling framework, and the most argued about.
Alignment
What It Does Well
Many teams working toward shared objectives.
Planning together
Big-room planning surfaces dependencies early.
A starting structure
Gives large organisations a map to begin with.
Heavy
Fair Criticisms
Many roles, layers and events to run.
Top-down risk
Can reinforce central control over team autonomy.
Adopted by certificate
Sometimes chosen for the badge, not the problem.
Sources: Scaled Agile, Inc.: A Decade in Adaptation: The Scaled Agile Framework, 10 Years Later ↗ · Scaled Agile Framework: Agile Release Train ↗
Borrow what solves your problem. Skip the rest.