Comprehensive Addiction Resources Emergency Act of 2021 This bill establishes programs, grants, and other activities to address substance use disorders. Specifically, the Department of Health and Human Services (HHS) must establish a program for purchasing and distributing opioid overdose reversal drugs for states and Indian tribes. HHS must also award grants for and otherwise support addressing substance use, particularly in states, tribes, territories, and localities with disproportionately high drug overdose rates; increasing access to preventive, medical, recovery, and related services; developing innovative models of delivering treatment and harm reduction services; and expanding the treatment capacity of Medicaid providers. In addition, HHS must issue model standards of care for treatment services and recovery residences and may award grants for training health care professionals. The bill also supports prevention and treatment services for workers, addiction and pain management research, and data collection on substance use disorders. Further, dispensers, distributors, and manufacturers of schedule II controlled substances (e.g., oxycodone), with the exception of opioid treatment programs, must certify that they maintain effective drug diversion controls. Violators are subject to specified civil and criminal penalties. Collected penalties shall be used for the grant programs and other substance use disorder activities established under the bill.