You can add collision to certain tiles on a tile map. What you do is create a new tile map, create a new tile set in the inspector tab on the right, and click on the tile set you just created. There will be a drop down menu called "Physics Layers" and you'll want to select "Add Element" and add select what physics layers you want everything to be. Then add in the tile set asset you want to use and select the Paint tab next to Select and Setup. In the dropdown under "Paint Properties" select the Physics layer you just created and select the tiles you want to have collision. This should make it so that your player can walk over any tiles that don't have collision. Hopefully this is what you were asking and is helpful!
