How to Make Tiles Larger
Hide the Ribbon & Status Bar:
From the Player ribbon --> Preferences --> Ribbon/StausBar, uncheck Show Ribbon & Show Statusbar.
This will give the tiles more room on the game board, thus they will appear larger. The ribbon can still be used by clicking any of the Ribbon tabs that still show.
Disable Proportional Tiles:
From the Player ribbon --> Preferences --> Tiles, uncheck Display Proportional Tiles.
When selected, this forces the layout to maintain the proportional shape of the tileset. When disabled, the tiles will stretch to fill the available screen space.
Use Layouts With Less Tiles:
Layouts with a larger amount of tiles will cause the tiles to appear smaller on the screen. Layouts with less tiles appear larger.
Mega 288 Tile Layout
Traditional 144 Tile Layout
Traditional Modified to 96 Tile Layout