If it's possible to pay for a paid course on udemy, it is a very good platform to learn motion graphics from but if you can't, there are so many free resource materials that you can be able to find on YouTube channels.
Motion graphics is really taking the fast lane, especially with social media contents.
For newbies, platforms like YouTube and Udemy are great places to start. Pay for some courses or choose the free courses, there are many resources materials available for it.