You should be able to get a list in File Explorer. If you don't have File Explorer (the manila envelope icon) pinned to your bottom task bar, I suggest that.

Select "This PC" or specific drive.
In the search window, use *.pdf as your criteria.

If you need to copy and paste that list:

Press Ctrl + A to select all items in the search results.
Press and hold down the Shift key. Right-click anywhere on the block of file names selected.
Find "Copy as Path" from the menu that comes up after that right-click. (That option doesn't appear unless you've done the Shift key first.)
Then you can paste your list into Excel, Word, etc.