Yes, tone ecualizer, but with tone eq I have a problem many times:
when you select any patch in the sky all of them are in the last step of the curve.
So you cannot expand the highlights using a toot that has no control points to separate that tones.
May be it is due to the linear scence processing, but then in tone eq nodes should be not equally spaced or be shown in a logarithmic scale with morre controls in the highlights.
Your image is underexposed in general terms to not burn highlights.
And you use exposure to compensate it and the tone eq to revert it and expand lights with good result.
But that image is not backiluminated and has not so much DR than a sunset or when the subject is in the shadows.
When you have the sky overexposed (let us keep the clipping effects apart and thinkg of an image with no clipped channels).
May it be that the opposite path works?
I mean lowering exposure a bit, and using tone eq to adjust?
The use of color balance to darken the sky is providing a good improvment for the photos I have tested, thank you.
I would not like to keep talking about highlight recovery here, as it really does not too much relation with tone mapping or sigmoid vs filmic comparation.
But it @anon41087856 local contrast technics in gamma compensated work flow can produce halos, but usually in high contrast border thansitions.
Usually are selections and strong tonal changes what produces your halos.
In a sky that LR or other software recovers from one or two channels being blown you have not that problems (except if you are really mad at dramatization).
In clouds or sunsets there are no hard borders or abrupt transitions, so recovering color from neighbourhood and aplying info about luminosity from the remaining channel usually does not work bad.
In any case it works much better than having a grey patch or a magenta color where it should be a not so saturated yellow.