Maybe you have already homebrew on your Mac. On a system with homebrew and without Julia you just call brew cask install julia once to install Julia. After that a simple brew update followed by brew cask upgrade suffices to get new Julia versions (a new version may not be available the same day it is published by the Julia team; but usually the homebrew repository lags at most a few days behind).
If you do not know homebrew, it’s a package manager for MacOS (a bit like apt for Debian/Ubuntu or chocolately for Windows). The homepage is https://brew.sh/
Another option may be JILL (I just read about it in another thread).