How can anyone know if they were really baptized with the Holy Spirit?

By the fruits!

If the tree is good the fruits are good, if the tree is bad the fruits are also bad. If, after that personal experience where one has experienced peace, immeasurable joy, and a desire to bring one’s light to the Light of Jesus’ Truth, one finds within
oneself complete changes, such as thoughts about people are the best, no more evil, desire for revenge, malice, sick jealousy, excessive suspicion; in language, words of faith, love instead of profanity; in my heart I desire to be in communion with those of faith and, above all, with God, through prayers, meditation and fasts, and always seeking to divert our feet from the path of evil.

Finally, to manifest a true Christian character, regardless of the circumstances and those around him, demonstrating in his way of being the Fruits of the Holy Spirit., This person was baptized, because the Fruits prove that YES.

The Lord Jesus said, “So every good tree bears good fruit, but a bad tree bears bad fruit.” A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. Every tree that does not produce good fruit is cut down and thrown into the fire. So you will know them by their fruits. Matthew 7: 17-20

See you at UNIVERSAL or in the Clouds!