Joomla Blog Universal Read More

Question

So I have this Joomla website going and I'm creating a blog page. All featured articles go into Menu "Blog" no problem. The problem comes when I need to add a "Read More". I know I can do this with the "Read More" button that each article has but I want to make it a universal read more. Either after so many characters or so many words add the "Read More". Is this possible through Joomla's admin panel? If not can I add some PHP in one of the files?