Although Rec.2020 is often described in conjunction with an HDR spec like HLG or PQ, by itself it mainly entails a broader color space, not greater dynamic range. So plain Rec.2020 is about equal to Rec.709 dynamic range.
Rec.2020 supports a wider color gamut but your ability to see that will depend on whether your monitor is capable of Rec.2020. Given a Quicktime video file, MacOS ColorSync will read the 9-1-9 NCLC tags and transform the incoming Rec.2020 color to whatever your monitor display profile is.
Newer Macs with 27" Apple Studio or 32" Display Pro XDR monitors, the new MacBook Pros with Liquid Retina Screens and the newest iPad Pros have a preset system which (on MacOS) is in System Settings>Display. By default that preset is P3-500 nits or P3-1600 nits. Those look pretty good if the Quicktime file is tagged properly.
Other Macs have the previous ICC color profile system, and they typically don't look as good on Rec.2020 material, but each one can be different.
So, we are in a transitional period regarding wide-gamut displays, and the issue is not what you see but what equipment your viewers have and what they will see. As mentioned above, this also includes the distribution system and playback software. It is a complex test matrix.