I tried to find "Edit page" option but could not find it.
Is it possible to add some
.js file into a specific view?
It looks like you are using the
To can find
Edit Page option and add a JS/ CSS customization you should switch back to
Classic Experience as the following:
Classic experience option.
This option sets the experience to classic, which is the previous, older experience for document libraries.
For more details check Switch the default experience for lists or document libraries from new or classic