I used to use gvm for this — https://github.com/moovweb/gvm.
But initial installation of go from scratch does not work for Big Sur as 1.4 does not have a binary for this OS (this command fails — gvm install go1.4 -B).
To use gvm, you can do this:
0. Install gvm —
bash < <(curl -s -S -L https://raw.githubusercontent.com/moovweb/gvm/master/binscripts/gvm-installer) (https://github.com/moovweb/gvm#installing)
1. Install go from the official site - https://golang.org/doc/install?download=go1.15.5.darwin-amd64.pkg
gvm install go1.15.5
gvm use go1.15.5 --default
sudo rm -rvf /usr/local/go/ (which will uninstall non-gvm version).