How to change site URL for new posts

Currently, my WordPress blog is hosted at:

https://www.skepticalraptor.com/skepticalraptorblog.php/

I have a pretty good SEO for that URL, but I have gotten regular complaints that it’s too long, especially when I include the article name.

I would like to get information on how to fix this. First, I want to shorten the URL to:

https://www.skepticalraptor.com/XYZ (or something useful).

I see how to do that in the administrative section, but what concerns me is that then all my previous 1000 posts will now have new URL’s, literally destroying links all over the internet to my website.

So, my question is simply: is there a plugin or method to change the URL just for new posts, or alternatively, changes the URL of all posts, but creates simple 301 redirects from the old URL to the new one without doing it one by one?