brew upgrade php : ( get the latest homebrew php packages )

$ brew install php@7.4 : ( Install php 7.4 )

$ brew link php@7.4 : ( create an alias to this keg-only version; see comments output during installation )

$ echo 'export PATH="/usr/local/opt/php@7.4/bin:$PATH"' >> ~/.bash_profile : ( Add the alias to your path; see comments output during installation )

$ source ~/.bash_profile : ( Reload .bash_profile to use the new settings immediately )