Protecting Children From Experimentation Act of 2021 This bill establishes a new criminal offense for performing gender reassignment medical interventions on minors. It also provides that a minor who receives such an intervention may bring a civil action against each person who performed that intervention. The bill defines these interventions as certain surgeries or the use of hormones to change the body of an individual to correspond to a sex that is discordant with the individual's biological sex. It excludes, however, interventions in cases where an individual has ambiguous external biological sex characteristics or where a physician has determined that an individual does not have normal sex chromosome structure, sex steroid hormone production, or sex steroid hormone action. An individual who performs these interventions on a minor is subject to criminal penalties—a fine, a prison term of up to five years, or both. A minor who receives these medical interventions may not be arrested or prosecuted for an offense under this bill.