The last MacBook Pro with user-upgradeable RAM memory was the 2012 MacBook Pro non-retina display models. Beginning with the MacBook Pro 2012 Retina models, RAM has been soldered in place with no slots for maximum reliability.
Once Apple figured out how to get really reliable SSD drives, they were soldered down as well, starting about the 2015 models.
On some recent iMacs, the RAM and drive may be upgradeable, but you have to remove the display-glass to access the slots.
on the most recent Mac-Pro, CPU and GPU are not user-upgradeable, but there are lots of PCIe slots, if you want to add slot-cards.
To get real user-replace-ability, you will have to pay dearly -- and be tied to previous generation technology, and previous generation speeds -- Build a gaming Tower PC.
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But when I say the CPU, GPU and RAM is all on one chip-carrier for maximum performance, that performance BLOWS AWAY all previous Intel Macs at far lower power, and everything, including Frames Per Second, goes WAY up.
The pathways between those items can run much faster, and the memory speeds and memory-access bandwidth to support really fast computation, modeling, drives, and displays is crazy-fast.
The Mac Studio can support up to four or eight displays a up to 6K resolution each. When extra displays are added, it does not slow down at all because special Hardware does the data transfers without substantial CPU intervention.
The newest Macs (including Mac Studio) feature ThunderBolt-5, which has potential for even faster data transfers up to 120 G bits/sec, and can NOT be added as a user retrofit to ANY system, Mac or PC.