If the sky is plain, there’s only so much composition can do—you either minimize it, make it more interesting in-camera, or accept it as part of the scene.

Useful in-camera options from the discussion:

• Change the sky’s tone with a polarizer, which can deepen blue sky and add contrast.
• Use a graduated filter if you want to darken or color the sky at capture rather than in post.
• Control exposure carefully to pull out whatever color or tonal variation is already there.
• Consider black and white if color in the sky is weak but tonal contrast is usable.

More broadly, be clear about your goal: are you documenting the building faithfully, or making a more dramatic image? That choice affects whether you wait for better light, crop tighter to reduce sky, or use the sky as negative space.

If the sky is truly featureless, sometimes it will simply look featureless. In that case, the main alternatives are to revisit under better conditions or use post-processing such as sky replacement—but that goes beyond your in-camera preference.