He is not a King.
Amendment 5:
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
Amendment 14:
...No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
That whole Due Process thingy is pretty well mentioned in the Constitution.
Additionally, Biden is neither the Legislature nor the Judicial branch: he has neither the Constitutional authority to make law, nor the Constitutional authority to judge those who are alleged to have violated law and impose penalties thereby. Those powers are (Constitutionally) reserved to the Legislative and Judicial branches, respectively.
He
can call for an investigation, which results should be remanded to those whose job it is to prosecute under the law any violations thereof, but, as they say,
"That's all, folks!".
My guess is that he's flapping his lips, again, unconnected to anything more cognitive than the effort to deflect accusations of caring more about Ukraine than Americans, especially considering the looming shutdown over appropriations.