Of course there is... but why would you want to?
I'm not being difficult here ;) but the point of using Photos is that it is your Photo Manager. It is to your photographs what the Contacts app is you your addresses and phone details for the people you communicate with. You don't want, or need, to access the individual names and addresses in the background. To add, edit or delete one you go to Contacts.app
Well same with Photos. To add, edit, delete or whatever you want to do with your photographs, you do either with or via Photos. There is literally nothing you can't do via the application. But there is a consideration: the actual library is set up run a quite specific way in the background and it is protected (lightly, I'll get to that) from Users making changes within the library. Why? Because making changes there can and will cause you dataloss.
If you want to look inside the library - and here's how light the protection is - simply right-click on the library package and select 'Show Package Contents' and you can see inside. It won't make a lot of sense to you, but then there are no user-serviceable parts within. So, look, make no changes of any kind, and leave. `;)
You can set up a different kind of Library where your files are stored in the Finder. This is called a Referenced Library but I strongly urge you never to do this with Photos as it simply has not got the tools to manage such a beast competently.
So, what do you want to achieve by accessing the files directly? Let us know and perhaps we can explain to you how to achieve what you need with Photos, or, if you're determined to have the file stored loose in the Finder, we can suggest apps that are better at working on that basis.