And the multitudes that went before, and that followed, cried, saying, Hosanna to the Son of David… – Matthew 21:9

My kingdom is not of this world… – John 18:36

Our Savior intended by this singular procession, to let His enemies know His real strength among the people. If he could gather so great a crowd of adherents without any summons or prearrangement, surely the whole population must have been, to a large degree, in his favor. If such an enthusiastic reception was spontaneously given Him, how many would have gathered if a plan had been arranged? Had He agreed to lead them against the Romans, thousands of fanatics would have followed His banner. If He had designed to make Himself a king, and had permitted His servants to fight, the old fierce courage of the Jewish race would have burned up like a flame of fire and His enemies would have fled before Him. He came not with war in His heart, but He would let the foeman see the hilt of the sword which He might have drawn from its sheath: He would let scribe and Pharisee bite their lips, while they said, “Perceive ye how ye prevail nothing? behold, the world is gone after Him.” If the Savior had willed to use the baser methods that men nowadays would freely employ, by asking the world’s alliance, He might have made Himself a King at once. Had He blended politics with religion, and yielded something to general prejudice, He might at once have set up a worldly kingdom. But no, He knew no selfish ambition, His kingdom was not of this world; He came not that He might be honored here, but that He might be put to shame for our redemption. The diadem to which He aspired was a crown of thorns; yet He lets His adversaries see that He was not lowly because He was weak, nor gentle because He was feeble. They might, if they would, have seen by that day in Jerusalem the greatness of the self-denial which abstained from earthly honors. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/2196.cfm