Essentially set the monitor to HDR 1000 or 400, whatever your preference is and leave it be. Then turn on/off HDR in Windows if your game does not support the HDR trigger signal to automatically turn it on/off within Windows.
It does work exactly like a TV but only if the HDR compatible game or application playing the HDR encoded video sees the HDR request from the content which then triggers the HDR mode within Windows which then shows Smart HDR On in the OSD of the monitor.
The state of Windows based HDR is that not all game or app developers do this properly, hence why talk earlier of some games automatically turning HDR on in Windows which then outputs the HDR signal to the monitor which displays it in HDR TB 400 or Peak 1000 depending on what is enabled in the OSD.
You won't know what games support the auto trigger feature without trying it. Just turn on HDR in the game settings and the monitor //should// flick to HDR, if it does not, you will need to manually turn HDR mode in Windows before launching the game.
A prime example of games that do auto trigger are Doom Eternal, the Resident Evil Remakes.
Games that do not auto trigger and need it enabled manually first in Windows: Plague Tale 2, Uncharted, Days Gone, God of War..
The alternative is to use the tool posted earlier in the thread above that auto triggers HDR if you add games/EXEs etc into the list.