Jumping in here, I’m on macOS and went through this just last week.
Adding to what Tom said, the process for how to update R on macOS is similar but slightly more manual. Head over to CRAN’s macOS section, download the latest .pkg file, and run it. It installs cleanly over the previous version, no need to uninstall anything.
RStudio generally auto-detects the new version, just like it does on Windows.
What helped me a lot was saving my package list before the update. Here’s what I do:
pkg_list <- installed.packages()[, "Package"]
save(pkg_list, file = "packages.RData")
Then, after the new R is installed, just restore:
load("packages.RData")
install.packages(pkg_list)
It’s not plug-and-play, but it saves you from the “which packages did I have again?” moment.