macOS Terminal autocompletion suggestion
You can use the zsh shell with the zsh-autosuggestions plugin.
- https://github.com/zsh-users/zsh-autosuggestions
This screenshot looks very much like the fish shell. This is an alternative shell to bash. One of its core features is smart auto-completion.
Alternatively you could use homebrew to install auto-completion for bash:
brew install bash-completion
You will have to press tab to complete the command you are currently typing. Press twice for all options -- if no unique completion exists.