Yes — the C1 is designed to allow this. Once you're in Indonesia on a valid C1 visa, you can apply to convert it into a longer-term permit such as a Retirement KITAS, Family/Spouse KITAS, or Investor KITAS, without exiting and re-entering the country.
Exact requirements and timelines depend on which permit you're converting to. Contact us early — ideally before your C1 visa or its extensions are close to expiring — so we can guide you through the right steps.