I don't believe you can just randomly substitute larger bars.
If you are substituting larger bars, but fewer, to provide the same area of steel, then the main problem from this would be the required development lengths and splice lengths required in the structure.
If you are substituting just higher bar sizes (same number of bars) you increase the area of steel and run the risk of creating over-reinforced members, which can be a bad situation with abrupt failures.
The answer you seek is "no".
Flexural members (Beams, beam-columns) are designed to fail when the reinforcement yields and provides warning in the form of crack widening before the concrete on the compression side reaches compression/brittle failure. Increasing the amount of reinforcement risks failing the member suddenly in compression.
A set of construction documents go together, and once sealed and permit is issued, the structure is to be build to plan. Changes have to go through a process of review to assure such problems are unlikely.
That said, there are many conditions and cases where such a substitute should be acceptable, but only after review by the engineer of record.
