You can enable tab completion of commands, subcommands, and options by configuring the completer included with the CLI tool.
On macOS, Linux, and Windows systems with a bash shell, you can load the completer with the following command:
complete -C 'which aws_completer'aws
By default, the aws_completer program is installed in /usr/local/bin. If your tool is installed to a non-standard location, you will need to find it and change the which aws_completer command to the relevant path.