The hardware on the N2 has quite a lot of flexibility for how the HDR->SDR conversion is handled, but there is no “correct”, optimal, or even good way to do this, since significant loss of dynamic range and color information is unavoidable, and the best choices may heavily depend on how your SDR display is configured, especially how high the backlight or equivalent setting is turned up and what brightness the SDR display is capable of.
It’s possible in the future there might be some configurability/different options for exactly how the mapping is done in CoreELEC, however:
TLDR: Most or even all consumer available HDR content have dedicated SDR masters also available. In almost all cases you’re better off watching this version if you have an SDR display. In this case the mastering has been done by a professional making the optimal and/or desired choices scene by scene, and is much better than any one-size-fits all conversion from HDR which can be done.