Amending the indictment
Section 601 of the Criminal Code allows a court to amend the indictment to conform to the evidence that has come out in trial.
In making the decision to amend, the court should consider whether the accused has been prejudiced in their defence by any omission and whether the amendment can be made without any injustice being done. For example, if the accused had already started to present their defence, based on the understanding that they were charged with X, but in doing so they hampered a potential defence with respect to not-yet-charged Y, it would likely be an injustice to amend the indictment to charge Y. Usually, the amendment is to alter the particularization of the charge (e.g. broadening the charge from an assault of a specific individual to an assault of a "female person": R. v. Ferguson-Cadore, 2020 ONSC 7094).
But there is also limited case law suggesting it is okay to swap in an entirely new charge (R. v. Bidawi, 2018 ONCA 698; R. v. Irwin (1998) 123 C.C.C. (3d) 316: "I see no useful purpose in absolutely foreclosing an amendment to make a charge conform to the evidence simply because the amendment will substitute one charge for another").
So, the final convictions do not need to be a subset of the initial indictment, but where there is a deviation, it is because a subsequent amendment has been made.
Lesser included offences
There is also the possibility that one would be convicted of a "lesser included" offence. The indictment is understood to include offences that are lesser included offences (s. 662). E.g a charge for aggravated assault includes the possibility of conviction for plain assault even if not explicitly stated.