To see HDR content at its full dynamic range, you'll need an HDR-capable device or display. Viewers watching on non-HDR devices/displays will see an SDR¹ video derived from the HDR source.
¹ "Standard dynamic range" or "smooshed dynamic range"
Not exactly - you need an HDR Mastering display to see HDR content at full dynamic range. There are essentially no high volume consumer-level devices, with the exception of maybe Apple's XDR lineup (MBP, iPad, iPhone, Pro Display) with the capability of displaying non-windowed HDR content at full brightness.
Everything else relies on tone mapping, even the latest 2022 OLED & QDOLED TVs.