Wizards of the Coast does not officially sell standalone PDF versions of their core 5e sourcebooks. Instead, they use digital platforms that provide a more interactive experience:

If you are searching for a it is important to understand the legitimate digital options available and what this "magical mixture" actually adds to your table. Official Digital Access vs. PDFs

Named after the legendary archmage Tasha (also known as Iggwilv), this book is packed with rules that change how the game is played: 1. Customizing Your Origin