macOS 10.12 Sierra represents a critical threshold in Apple's ecosystem. It was the last version of macOS to support certain hardware, such as the 2009 and 2010 MacBook Pro and iMac models. Consequently, users often seek out the Sierra DMG for two primary reasons:
If you need to install Sierra, the safest method avoids "repacks" entirely in favor of official tools: mac os sierra 1012dmg download repack
There is a safer way — even if you can’t find the official download anymore. macOS 10