No. Jesus was making changes to the Law (even before the New Covenant went officially into effect with His death). For Jesus was primarily teaching New Covenant teachings and not Old Covenant teachings during His earthly ministry.
How so?
Jesus clearly was making changes to the Law (even before the cross):
(Which means He was not teaching primarily Old Covenant, but New Covenant):
The Old Way says:
"Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth"
(Matthew 5:38 cf. Exodus 21:23-25).
The New Way (by Jesus) says:
"But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also." (Matthew 5:39).
The Old Way says:
"Ye have heard that it was said by them of old time, Thou shalt not kill; and whosoever shall kill shall be in danger of the judgment" (Matthew 5:21 cf. Numbers 35:30-32).
The New Way (by Jesus) says:
"But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire." (Matthew 5:22).
The Old Way says:
"Again, ye have heard that it hath been said by them of old time, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths:" (Matthew 5:34 cf. Numbers 30:1-2, Deuteronomy 23:21).
The New Way (by Jesus) says:
34 "But I say unto you, Swear not at all; neither by heaven; for it is God's throne:
35 Nor by the earth; for it is his footstool: neither by Jerusalem; for it is the city of the great King.
36 Neither shalt thou swear by thy head, because thou canst not make one hair white or black.
37 But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil." (Matthew 5:34-37).
The Old Way says:
"And of thy mercy cut off mine enemies, and destroy all them that afflict my soul: for I am thy servant." (Psalms 143:12).
"And the city shall be accursed, even it, and all that are therein, to the LORD: only Rahab the harlot shall live, she and all that are with her in the house, because she hid the messengers that we sent." (Joshua 6:17).
"And they utterly destroyed all that was in the city, both man and woman, young and old, and ox, and sheep, and ass, with the edge of the sword." (Joshua 6:21).
16 "But of the cities of these people, which the LORD thy God doth give thee for an inheritance, thou shalt save alive nothing that breatheth:
17 But thou shalt utterly destroy them; namely, the Hittites, and the Amorites, the Canaanites, and the Perizzites, the Hivites, and the Jebusites; as the LORD thy God hath commanded thee" (Deuteronomy 20:16-17).
"They did not destroy the nations, concerning whom the LORD commanded them" (Psalms 106:34).
The New Way (by Jesus) says:
"But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;" (Matthew 5:44).
Note: Yes, I am aware that the Old Way (Old Testament) also teaches to love one's enemies (Exodus 23:4-5) (Proverbs 25:21), but this was in context to their own Israelite people, and not pagan nations. Pagan nations were to be destroyed when God commanded the Israelites to destroy them. But Jesus taught a radically different way. Love your enemies, and do good to them that hate you, and to pray for those who persecute you.
The Old Way says:
20 "But if this thing be true, and the tokens of virginity be not found for the damsel:
21 Then they shall bring out the damsel to the door of her father's house, and the men of her city shall stone her with stones that she die: because she hath wrought folly in Israel, to play the whore in her father's house: so shalt thou put evil away from among you.
22 If a man be found lying with a woman married to an husband, then they shall both of them die, both the man that lay with the woman, and the woman: so shalt thou put away evil from Israel." (Deuteronomy 22:20-22).
4 "They say unto him, Master, this woman was taken in adultery, in the very act.
5 Now Moses in the law commanded us, that such should be stoned: but what sayest thou?" (John 8:4-5).
The New Way (by Jesus) says:
"He that is without sin among you, let him first cast a stone at her. " (John 8:7).
Oh no! Christ was not changing the Law, He was doubling down on it.
He was showing the depth of the Law in the spiritual side as well as the physical.