It has to depend on the engine, namely the materials used.
It for an aluminium alloy block and head, like on the VMax, I would say clearance increases as the alloy expands more so the camshaft moves a tiny amount from the valve buckets.
But in a cast iron block and cylinder head, it would decrease as the valve train expands more than the cast iron. My Ford crossflow engine (cast iron head/block OHV) ran quieter when hot.
Disclaimer: I'm not entirely sure.