hdr tonemapping nits metadata

[geextahslex]

Hi, I would like to know if there is a way to let the metadata make the picture darker but not brighter, because making it brighter desaturates dark scenes and makes them look weird. But making bright scenes darker is a nice feature for prevent overexposure.
Something like a threshold or ratio. Or vf=format=sig-peak=min max?

Thank you :)

here you can see the desaturated image, it looks washed out

here it is set to vf=format=sig-peak=4.926 and looks normal