If the file doesn't download automatically, tap (three dots) and select Downloads to manage your files. Download a file - Android - Google Chrome Help
Press Ctrl + Shift + F inside a Doc to hide the menu bar and expand your workspace.
To help you find such resources or perform a similar search yourself, you can use these to locate and download PDF guides: How to Find PDF Guides for Google Docs
Based on popular guides found in PDF format, here are some helpful features you might be looking for:
This will return only PDF documents, such as the 149 Amazing Google Tricks guide, which includes time-saving features like "Dragon Slain" in spreadsheets or custom document templates. Essential Google Docs & Search Features
When downloading PDFs from search results, ensure you are using a trusted source. Open the link in your browser (e.g., Chrome).
In a Google Docs spreadsheet, press Shift + F12 to see a "Dragon slain!" congratulatory message.
site:website.com : Search for content only within one specific website. Downloading Files Safely