“Best practices” smells like such a marketing term it should be tossed in the bin.
It’s poetic language that has nothing to do with specific problems.
What people usually mean when it comes to engineering is “be safe, reliable, and correct.”
Security best practices to be safe.
Developer best practices for reliability.
Etc etc
“Best practices” is hand wave-y fluff for “do a good job” and doesn’t need a technical definition.
Make sure you’re secure, reliable, and correct given the engineering context, and odds are you result in a system that also has a lot of specific best practices in place.