So, one could boost highlights before AgX.
Left: image without tone mapper (gamut check shows the sky is actually out of gamut, but looks more or less OK here). Right: filmic, auto-tuned. No other changes.
Left: original image. Right: AgX, auto-tuned. No other changes. The saturation of the sky is reduced, the sunlit face looks quite flat.
Left: filmic. Right: AgX.
Left: filmic. Right. AgX, with 60% hue preservation and color balance rgb with perceptual saturation boosted for highlights:
There is more highlight contrast in filmic, more midtone/shadow contrast in AgX:
One could move the pivot higher (I sampled the sunlit face of the building), and increase contrast – and then color balance rgb is no longer needed (it’s turned off here):
Split mode:
