Design of a Flyback transformer for SMPS

Hi, how are you? Thank you in advance for reading the topic.
The question is that I have been interested in the QC 4.0 and usb PD 3.0 charging protocol but in most of the reference designs there is missing information of the flyback transformer and how to design it only comes that nucleus they use that is usually the RM series- 8 or RM-10,
One of the reference model I found is the
I do not know if there are already series of these transformers for converters up to 45W or if there is a design format to send them to be manufactured.
If you can help me with this I would really appreciate it