There are loads of great online training courses and content on for Google Analytics 4. Some are suitable for beginners and some are for more experienced users but all of the ones i've highlighted below are from reputable providers:
Official content from Google
- Official GA4 accreditation
- Official GA YouTube channel
- Google’s official learning path
- Google presentations on GA4 reporting interfaces & data
Helpful Youtube channels
- AnalyticsMania by Julius Fedorovicius
- KS Digital by Krista Seiden
Useful paid training courses
- AnalyticsMania (Julius Fedorovicius)
- KS Digital (Krista Seiden)
- CXL
- Jellyfish
Do let me know what you think of these or if you come across any other great ones and I can add them to the list!