Combatting Fentanyl Trafficking from China and Mexico Act This bill requires the Department of State to carry out programs and activities to prioritize efforts to combat the international trafficking of certain synthetic drugs and precursor chemicals from Mexico and China. Specifically, the State Department shall strengthen law enforcement and rule of law efforts outlined in certain agreements between the United States and Mexico, strengthen bilateral efforts, and provide Mexico with technical assistance and equipment for anti-drug law enforcement. The President may impose certain sanctions on persons of China determined to have engaged in or benefited from the international proliferation of illicit drugs or their means of production. The President may terminate sanctions on Chinese persons upon determination that China has made substantial efforts in counternarcotics. The bill also authorizes through FY2027 State Department International Narcotics and Law Enforcement for Mexico, Customs and Border Protection interdiction programs, and a Department of Homeland Security transnational criminal investigative unit with Mexico.