turn-key

/T ER1 N K IY0/
adjective
  1. 1

    Ready to use without further assembly or test; supplied in a state that is ready to turn on and operate (typically refers to an assembly that is outsourced for manufacture)

    They wanted a turnkey solution for the entire system, but we could only provide the enclosure.

Source: https://en.wiktionary.org/wiki/turn-key, https://en.wiktionary.org/wiki/turnkey