The form of the Mass is not a doctrine or dogma. It is part of the disciplinary laws of the Church and it can be changed. The only part that cannot be changed are the words of consecration.
In case you are referring to QUO PRIMUM by Pope St. Pius V - July 14, 1570 and the statement therein “Therefore, no one whosoever is permitted to alter this notice of Our permission, statute, ordinance, command, precept, grant, indult, declaration, will, decree, and prohibition. Should know that he will incur the wrath of Almighty God and of the Blessed Apostles Peter and Paul” this has nothing to do with doctrine.
Popes cannot change dogmas and doctrines but they can change laws, including those passed by previous popes. Popes know that disciplinary laws are not eternal.
With Quo Primum the Pope is saying that no one may alter the decree that he was issuing. In other words, if some King or Bishop made changes to the Papal decree, he would incur the penalties threatened. The Pope was dealing with a situation where there was much confusion caused by the protestant revolt, which began in 1517, and by lack of education among some Catholic clergy, including even some Bishops. Therefore he forbid anyone to alter his decree. He did not, and could not, forbid future Popes to do what he himself was doing and that was passing disciplinary laws for the good of the Church.