Yes. There are various kinds of modifiers available in Minecraft. Which are -
Hollow: The main purpose of this is to make the hollow types rectangular from inside.
Replace: It replaces all blocks with another block. For example, /fill Minecraft:diamond_block replace Minecraft:clay
Destroy: It breaks all the blocks and turns them into items. As a result, you can pick it up.
Keep: Inside the rectangle, it will fill the air and leave blocks.
Outline: The blocks which you have already chosen and placed, will be outlined if you use these modifiers after the fill command.