No fixed grid is used on this Scene allowing free-form point-to-point measurement without grid lines.
A square grid is used with width and height of each grid space equal to the chosen grid size.
A column-wise hexagon grid (flat-topped) where odd-numbered rows are offset.
A column-wise hexagon grid (flat-topped) where even-numbered rows are offset.
A row-wise hexagon grid (pointy-topped) where odd-numbered columns are offset.
A row-wise hexagon grid (pointy-topped) where even-numbered columns are offset.
The allowed Grid types which are supported by the software
https://foundryvtt.com/article/scenes/