The engine makes a ticking noise when started cold but goes away. What is it?

There's some wear on the valve train , a rod/lifter is worn . You can try mechanic in a can conditioner/thinner oil and it may help but it will only get worse . IMO

It ticks on initial start up but is fine the rest of the day then it’s a lifter getting weak, now the right way to fix this would be to replace the cam and all the lifters with new ones. But I have seen backyarders just replace the bad lifter and get away with it, but they have no liability like a good shop who would do it right.

I’ve heard lots of engines doing the same thing , it’s a lifter . To replace it is quite expensive and then need to do them all. Keep your oil changed and as long as it runs like it should I would drive it.