There was baptism and marriage long before Christ.. He did not "institute them ... he never ordained anyone ..he never gave "last rites" .. The only sacrament he instituted was the Lords supper.. and even that had previously been the passover meal..now done to remember the cross not the passover of the jews..
Baptism — by John the Baptist — He said, “I am baptizing with water, but one is coming after me who will baptize with the spirit.”
That means grace from Christ.
Marriage — At the Wedding of Cana, the first miracle worked by Christ — he sanctified the sacrament by turning the water into wine. And did you know that the sacrament of matriomony is between the man and the woman WITH God?
Yes, in both Sacraments, grace is extended through Christ.