Let’s address the elephant in the room. I know exactly why you are searching for "ISO 2768 standard PDF." You want a clean, official copy without paying the $150+ CHF that ISO charges.
Simply put: You cannot realistically put a tolerance on every single corner, chamfer, hole depth, or angle in a complex part. If you tried, the drawing would be unreadable. Instead, you use ISO 2768. It applies to all dimensions that do not have a specific tolerance written next to them. iso 2768 standard pdf
This section focuses on the permissible deviations for "size" features, including internal and external dimensions, diameters, radii, and chamfer heights. It defines four tolerance classes: Let’s address the elephant in the room