There are plenty of Password Generator websites and apps out there. Type in password generator or password manager in your favorite or least favorite search engine and you will get more than you should ever need. They range from lousy to awesome. Ideally, at a minimum an app or website should let you set the length of the password. I found this one today, https://passwordsgenerator.net/, This one has the added advantage of allowing random name generation – https://passwordsgenerator.net/name-generator/. Often, a website will dictate the rules for passwords and not all Password Generators allow you to set the rules in ways that work for a particular website.
My suggestion is to try out several different ones and see which one(s) do what you want in ways that work best for you.