The situation I’m think of is a Pokémon holding the Item Metronome uses Flamethrower 1 turn. If it the Pokémon Dynamaxed the next turn would’ve boost reset and Max Flare do 1.0 damage. Or, keep the boost and do a extra .2 damage per use.
Max Flare and Flamethrower are both moves that are connected yet aren't the same move I will say it won't work because Max Flare is a different move that has different effects then other moves. When you go to the link for Max Flare you will notice that it changed normal moves to dynamax type moves which seems to mean that the move won't be the same.