Sync - the very unApple-like user friendly process

Apple generally ranks high in User friendly procedures, however I seem to be in the small percentage of people who encounter problems...

I have an iPhone XR, and a Mac mini (late 2014 model). I am logged into both using the same Apple ID.

I want to simply have the same contacts list shown upon both.

Now for some reason or other, which I have yet to figure out, as I am not an Apple expert, my list of contacts shown upon my Mac mini, is not the same as that upon my iPhone.

So, how do I push my contacts list from my iPhone to my Mac ?

Both are connected via the iCloud with Contacts selected as Cloud enabled, though I previously had not shared my iPhone contacts with the iCloud, I simply turned it on, in order to facilitate the transfer...

How do I make merge one to the other without overwriting data ?