Hard to say without knowing what settings you're using, but you could try the following:
1. Use a window light facing up to the ceiling at about mid-level on the columns to lighten the ceiling.
2. Reduce the 'diversion angle' on the Sun Object to 1 degree or less to sharpen the shadows. Make sure the Sun Object has a yellow tint and the
Sky Object has a blue tint.
3. In the Photorendering Settings, make sure you haven't checked 'Fog' under the Foreground settings.
4. Get rid of the dead grey sky in the backgound photo and use a nice blue sky to liven up the image.
Cheers.
PS - You should also attach details about your hardware & software.
Cameron Hestler, Architect
Archicad 27 / Mac Studio M1 Max - 32 GB / LG24" Monitors / 14.5 Sonoma