The iMac 27-inch (2020) has a RAM door — one of Apple's most user-friendly designs

Apple actually made RAM upgrades pleasant on the 27-inch iMac (2020) — there’s a small door on the back you pop open with a coin or flathead screwdriver, and four SO-DIMM slots sit right there waiting. No prying, no glue, no heat gun. It’s one of the last great user-serviceable designs Apple made before the Intel-to-Apple Silicon transition killed it off.