Sure, you can do that. The first thing is that you have to name your mascot. Then, you need to open some social accounts against the mascot name. and then, create your virtual world. Decorate the world with objects, items and ideas.
Gradually, your mascot will get popular and it will be a brand, someday.
Alternatively, you can use the mascot in your real-life situation. The mascot may play roles in local, national and international events. The media coverage will earn you a lot of business opportunities that you will never want to miss.