Hi @frankie.sc.law welcome to the forum.
The TL;dr for knowledge files is
### Knowledge Files
1. Convert all text files (.pdf, .docx, etc.) to text files. Ideally format as Markdown (.md). .txt is fine too.
2. Convert all table files (.csv, Google Sheet, etc.) to .xlsx as ChatGPT works especially well with Excel files.
3. Per GPT Limits: 10 files
4. Per File Limits: 512MB (20MB for image files, no limit for .xlsx), 2M tokens
5. Per User Limits: 10 GB. Per Organization Limits: 100 GB.
6. Direct uploads to Knowledge are recommended for performance.
7. Separate content into smaller files for better search efficiency.
8. If knowledge is frequently updated, do not upload the file. Instead use a system to store the file or url and create an OpenAPI endpoint to fetch the content via an Action.
I am keeping track of these limits as this changes over time here as a quick reference for anyone.