Just press and hold the "INFO 123" button on the Samsung remote.
And yes, it is mentioned in the manual on page 10 under the "Tour of the Remote Control". Easy to miss.
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As a followup, I had many problems with this, but discovered it was the crappy remote control. So I programmed my main remote with the IR signal for that one key and now I can bring up the calibration charts, skip ahead to the PLUGE and check the clip point in nits after pausing the image. I have confirmed that these charts send HDR metadata to the projector and give me a proper calibration reference for black level and peak white capability.
The Sony 665ES can display up to 3000nits peak white before clipping with UHD HDR disk playback. This is with contrast set to maximum in the projector and default "standard" in the Samsung.