I doubt that Trump understood the historical references. I doubt that Trump knows what the Magna Carta is or what it means. Here was the King of England praising the document in his own country's history that curbs the power of the king. He used it to reaffirm the principle of the balance of powers in government that our own Constitution established here, but which Trump ignores.

Trump would not have stayed awake through the speech. His staff will need to summarize it in bits that he can digest.

I hope that the speech inspires action in Congress to uphold the values and governance that Charles spoke of. I doubt that it will inspire Trump. To Trump, the presence of British royalty in the US represents White European origins and supremacy even though the king praised the strength of the UK and US as coming from the input of diverse people in our nations.

And even if his staff summarizes it for him, he'll likely think he knows better. He's just impressed the British royalty came to visit HIM. But I share your hope that what Charles said in his speech will inspire/motivate some in Congress.