You seem to be referring to a hypothetical scenario as currently I couldn’t find any verified news reports about the House GOP taking steps to hold Attorney General Merrick Garland in contempt over a subpoenaed Biden audio. However, the House GOP or any congressional committee can decide to hold a person in contempt if they believe that person is not complying with a subpoena or obstructing a congressional investigation. This process can lead to a criminal referral to the Department of Justice. Please remember to check the source of the information,