Hemi piston slap?

One of my 2018 6.4 2500 have been cold knocking since new.
Smells like antifreeze after a hard drive and shut off. Dealer states it’s normal.
Always running the 0w20 oil from Pennzoil like factory says. Never down on oil or antifreeze. Quirky Chrysler’s.
When cold sounds like a rod is knocking.
I start it up and run away till it warm.
Dealer head tech told me it’s something to due with lifter noise. Smell is coolant cap release.

40k on that truck and it does it every morning.