There are a lot of crossword constructors who publish/sell their puzzles independently on the Internet, and often they create both puz and pdf files. Some sources of free ones:

- Brendan Emmett Quigley: https://www.brendanemmettquigley.com/

- Paolo Pasco: http://gridsthesedays.blogspot.com/

- and see the sidebar of Paolo's blog for links to many more constructors

- They stopped publishing these online, but the Chronicle of Higher Education has several old crosswords here: https://www.chronicle.com/section/Crosswords/43