Lower Health Care Costs Act This bill makes a series of changes relating to health care coverage, costs, and services. Among other things, the bill applies in-network cost-sharing requirements to certain emergency and related nonemergency services that are provided out-of-network, and prohibits health care facilities and practitioners from billing above the applicable in-network cost-sharing rate for such services; revises certain requirements in order to expedite the approval of generics and biosimilars, including requirements relating to citizen petitions, application effective dates, and labeling; requires health care facilities and practitioners to give patients a list of provided services upon discharge and to bill for such services within 45 days; limits prices that pharmacy benefit managers (PBMs) may charge health insurers or enrollees for prescription drugs, based on prices paid by PBMs to pharmacies; establishes grant programs to support vaccinations and data modernization; and requires health insurers to make certain information, including estimated out-of-pocket costs, accessible to enrollees through specified technology (e.g., mobile applications). The bill also makes several additional changes relating to public health, including raising the minimum age to purchase tobacco products from 18 to 21.