Using tilesets uses just as much resources as if they were meshes (which they already technically work). How they operate is you create a tile sheet and set numerous frames for the dimensions you want to use. You can then make so if you were to change the tile resolution to a certain w x h, it will display that specified tile. Then within the each frame you can place meshes and props to your hearts content. This specific tileset randomly picks from several frames with different varieties.
Generic tile setup:
Here’s a great tutorial on how these things work:
Additionally you can instantly convert these tilesets to their original mesh.