Sahih Muslim (810) reports that the Prophet ﷺ asked Ubayy ibn Kab which verse in the Book of Allah is the greatest. Ubayy answered by reciting Ayat al-Kursi, beginning with "Allah, there is no god but Him, the Ever-Living, the Sustainer". The Prophet ﷺ struck his chest and said, "May knowledge be easy for you, Abu al-Mundhir." This is how the Prophet ﷺ praised his knowledge.
Sahih al-Bukhari (2311) reports that Abu Hurairah (may Allah be pleased with him) was guarding the zakah stores when a thief came, who was in fact Shaytan. He taught Abu Hurairah to recite Ayat al-Kursi when going to bed, and said that a guardian from Allah would stay with him and Shaytan would not come near him until morning. The Prophet ﷺ said, "He told you the truth, although he is a liar." So reciting it before sleep is a sound, established practice.
Another report says that whoever recites it after each obligatory prayer has only death standing between them and Paradise. It is recorded in the Sunan al-Kubra of an-Nasai and elsewhere. Scholars differ about its grade: some graded it hasan or sahih, and others considered it weak. Reciting Ayat al-Kursi after prayer is a good remembrance of Allah that many scholars recommend, but the specific reward in this report should not be treated as established in the sahih collections.
These reports are about the reward and the protection that come with sincere belief. The verse is not a charm that works without faith.