When you have non-HTML pages on your internet site, such as PDFs or spreadsheets, you won’t be capable to implement hreflang within the of the HTML because it doesn’t exist.  Canonical tags are certainly not the sole technique to declare a website page’s canonical. You should use 3 other methods: https://guidemysocial.com/story4157491/5-easy-facts-about-hreflang-to-non-canonical-described