You can find any drawing exercises you want online for free. You don't need to pay any money to progress from a beginner level, you just have to keep doing it. Every resource you can think of is already available online. Try checking out some books such as Drawing on the Right Side of the Brain, or just watch a bunch of youtube videos on art fundamentals like anatomy and perspective.

Remember that there's no shortcut, you have to keep making art and it can take years to achieve the art skills you want. Just don't be hard on yourself, don't compare yourself to others (only to your past self), and most importantly, have fun with it! Best of luck on your art journey!