Is it possible to merge sprites/textures for a tiling engine?

[Merle]

I always thought people just drew every single tile and wrote one long if-else statement to check which sprite to load, but now I realized there are way too many possible block formations to do that. How do people normally approach auto-tiling? Is it possible to have one sprite of the border of a tile, and then instead of loading a million different tiles, just merging the border on top of the original tile texture?

[Hapax]

Grid-like tiling?

You can use a single vertex array (set up to draw quads) to draw the entire visible "tilemap". There is even a tile map example within that tutorial!

You can also consider using Selba Ward's Tile Map, which does all this for you