Concerning the Mercy Seat of the Ark of the Covenant and a foreshadowing of Messiah’s atonement,
Leviticus 16,
11 “Aaron shall bring the bull for his own sin offering to make atonement for himself and his household, and he is to slaughter the bull for his own sin offering. 14 He is to take some of the bull’s blood and with his finger sprinkle it on the front of the atonement cover; then he shall sprinkle some of it with his finger seven times before the atonement cover.15 “He shall then slaughter the goat for the sin offering for the people and take its blood behind the curtain and do with it as he did with the bull’s blood: He shall sprinkle it on the atonement cover and in front of it. 16 In this way he will make atonement for the Most Holy Place because of the uncleanness and rebellion of the Israelites, whatever their sins have been.”

The fulfillment of all the Mercy Seat and Day of Atonement foreshadowed,

11 But Mary was standing outside the tomb, weeping; so as she wept, she stooped to look into the tomb; 12 and she *saw two angels in white sitting, one at the head and one at the feet, where the body of Jesus had been lying. 13 And they *said to her, “Woman, why are you weeping?” She *said to them, “Because they have taken away my Lord, and I do not know where they put Him.” (Gospel of John, Chapter 20)

Overview,
Mary observed the blood of Messiah staining the stone upon which His body has been laid along with the two-angels, one sitting at the feet…one at the head of the actual mercy seat foreshadowed by the Ark of the Covenant. Jesus, alone, is our atonement for the sin of the whole World (1 John 2:2).

The Ark of the Covenant foreshadowed Messiah Jesus,

The Ark’s wood represented Messiah’s humanity.The Ark’s gold represented Messiah’s deity.

The Mercy Seat represented Messiah’s atoning blood sacrifice.

The pot of manna within the Ark represented that Messiah would be Bread of Life (John 6:35).

Aaron’s rod within the Ark that was a dead-stick but budded to life represented the death and resurrection of Messiah.

The Tablets of Stone, the Commandments, within the Ark represented that the Messiah would be the fulfillment of God’s Law and that God’s Law representing God’s holiness and righteousness would be integral within Messiah as the Son of God and the Son of man.