macOS does not have Bash autocomplete feature installed and enabled by default as Linux distributions like Ubuntu does. You will have to install and configure bash-completion program for macOS to enable it which is available via Homebrew.
bash-completion can be installed and enabled in macOS from the terminal.
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
$ brew install bash-completion
$ . /usr/local/etc/bash_completion
[ -f /usr/local/etc/bash_completion ] && . /usr/local/etc/bash_completion
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