<blockquote>In the game I'm currently working on, I'd like the player's movement on the map to be a grid like a simulation game, and the battles to be turn-based.</blockquote>
Do you have an example of a game with what you're after? To me, it sounds sort of like a Mystery Dungeon setup?
In that case, what you'd probably want to do is have your movement handled through a custom controller along with environmental design. Design your maps to be a grid, and use the Battle Grid component to generate the grid (matching Tile size).
Then when outside of combat, the player controller just moves +1/-1 rather than the interpolated input of normal games. Upon contact or a certain range of enemies, you then initiate battle which moves to the Grid Turn Based system. As long as your tile sizes match, you should effectively have that same result. Another route I think you can take is one giant battle running at the start, but that might have a few hangups with AI / wait time depending on size.
If you just mean they move in a grid but then it moves to a standard turn based game, sort of like the super old school Dragonquest or Final Fantasy (or RPGMaker I suppose?), then you'd just design the 2D layout and controls as you would for that game, and then use a new scene for battle to change sprites + layout (or models if 3D). Definitely do-able.