Pope Francis has recently ordered parishes to start including women in the Rite of the Washing of the Feet on Holy Thursady following the Mass, saying that the people whose feet are washed should "represent" the parish. When it comes to the Rites, Practices, and Liturgies of the Catholic Church, does the Pope have supreme unilateral power to change them, amend them, abolish them, elongate them, etc.? The Second Vatican Council reformed the Mass and did that as a Catholic ecumenical Council and was not done strictly by John XXIII and followed up by Paul VI. I know that Pius XII had instituted some reforms for the Rites of Holy Week, but I don't know how far those went to altering what had been celebrated prior.
Can the Pope, for instance, say that the Canon of the Mass is now forever abolished? Can the Pope decree that altar servers must "represent" the parish? Can the Pope decide that the Crucifixes be removed in favor of crosses without the Corpus? Are there limits? If so, what?