I'm always amazed at what you can find by just doing a Google Search:
https://suvivaarla.com/sheet-metal-drawings-for-practice-pdf/
Here are two recent GRABcad tutorials on CATIA sheetmetal
Part 1: https://grabcad.com/tutorials/catia-sheetmetal-design-smps-cover
try lynda.com tutorials+ watch manufacturing videos of sheet metal.
+ practice 2-3 times models given in youtube.
Drafting details with flattening and unflatten/bend view is also important for the manufacturer.
Sheet Metal Enclosure Design For PCB, Electrical & Electronics Products (smlease.com)
Sheet Metal Gauge Chart: Standard Sheet Metal Gauge to Thickness (smlease.com)
Difference Between Blanking, Punching & Piercing in Sheet Metal - (smlease.com)
Sheet Metal K-Factor, Bend Allowance and Flat Length Calculations (smlease.com)
The videos from the CAT SPIDER are great!