There are five grid sizes provided to the users on Locale.
City (8.5km) - Largest size
District (461m)
Locality (174m)
Neighborhood (66m)
Building (9m) - Smallest size.
Different grid sizes on Locale.ai
You can change the hexagon size by selecting the Grid size option from the toolbar at the top of the screen. In the dropdown menu, choose the grids option and then choose the desired size.