In general, people tend to excel at things that interest them. As new to coding, you may not yet know what interests you. My opinion about additional certifications is that you should consider only once you know what engages you or is required for your career path. Additionally, many jobs may require you to work in multiple specialties. I would not be concerned at this point in your journey to focus on specialty. The AAPC website even states for most of the specialty certifications, you should have experience in that specialty for 2 years. If you strongly want an additional certification after CPC, I would recommend certifications that apply to many specialties. CPB, CEMC, CRC, documentation. Focus on your CPC for now. Then focus on finding a position in the field. After experiencing different aspects/specialties, decide if specialty certification is for you.
Good luck!