Sober Truth on Preventing Underage Drinking Reauthorization Act or the STOP Act This bill reauthorizes through FY2027 and revises grants and other activities for reducing underage drinking. In particular, the bill modifies the scope of certain activities to incorporate a focus on the adoption and enforcement of state laws and policies for preventing and reducing underage drinking. This includes (1) assessing in annual reports whether states have adopted best practices related to laws, regulations, and enforcement practices; and (2) establishing a pilot program to collect uniform data from states and localities about their enforcement of underage drinking laws. In addition, the Substance Abuse and Mental Health Services Administration must contract with the National Academy of Sciences to review the research literature regarding the influence of drinking on adolescent brain development.