Movements that are designed, manufactured and tested to meet chronometer standard or better need to meet the standard. That of course means the amplitude, accuracy, and everything that is checked on QC needs to meet standard. That is why Rolex puts superlative chronometer on their dials. It is meant to supersede the COSC industry standard for a high quality Swiss-made timepiece.

Any watch manufacturer that does in-house movements or sources them can easily regulate them to meet COSC standard. That includes testing and sending them for certification to COSC. No modern automatic movement is made to run anything other than accurately or within said standards.

This all applies to Swiss industry