is the timing chain a replace as needed only item?
 

I'm somewhat mechanically inclined but haven't wrenched on the Camry much....my son has a 2016 4 cylinder, which I believe has a chain rather than timing belt. he currently has about 115k on the odometer. is the timing chain on this vehicle one that should be replaced at a certain interval or is it considered 'lifetime" unless weird engine noises?

Lifetime unless weird noises.

If the timing chain area starts to make a rattle noise the chain tensioner may be wearing out. Make sure it is the timing chain setup and not the water pump or a serpentine belt idler. You can use a section of rubber hose as a stethoscope to narrow down the area of any noises. Youtube would have videos of this model engine and any noises it might make for a reference.