Kickstarting Innovative Demonstrations Supporting Kids Health Act of 2023 or the KIDS Health Act of 2023 This bill requires the Centers for Medicare & Medicaid Services (CMS) to implement a demonstration program that supports a whole child health model for children under Medicaid and the Children's Health Insurance Program (CHIP). Specifically, the CMS must award grants to up to 15 states to plan and implement a health care model that supports the physical, behavioral, social, and other needs of children who qualify for Medicaid or CHIP through care coordination and integrated supportive services. States must implement models for 4-6 years. The CMS must provide technical assistance and guidance to states for the demonstration program. The bill also provides for an 80% federal matching rate for program costs. The Government Accountability Office must report on program outcomes.