http://ssd.iykpqm7jiradoeezzkhj7c4b33g4hbgfwelht2evxxeicbpjy44c7ead.onion/ps/module/how-use-keepassxc
You might want to do this when you are signing up for a new website, or when you are replacing older, weaker passwords with new, unique, random passphrases. After you click the dice icon, a password generator will appear in the window. You can use this to generate a random password. You'll be presented with many options, including what sorts of characters to include and how long to make the password.