That's a great and very practical question! In most cases, standard outdoor trash cans or garbage bins do not come with liners or bags included when you purchase them. The typical purchase includes just the container itself, and sometimes a lid. You will almost always need to buy trash bags separately.
This is standard for a few reasons. First, liner sizes and types vary greatly based on personal preference and use (like standard bags, drawstring bags, or heavy-duty contractor bags). Second, including a liner that might not fit perfectly or suit the buyer's needs could create more waste and dissatisfaction. Manufacturers leave the choice of liner to you.
However, there are some exceptions. Certain specialized or high-end outdoor trash systems, especially those designed for specific bag types or as part of a coordinated set, might include a starter roll of liners. Always check the product description or packaging for phrases like "includes liners" or "liner not included" to be sure.
My advice? When you buy a new outdoor can, note its exact dimensions (gallons and inner rim measurement). Then, look for bags labeled for that gallon capacity. A proper fit prevents bags from slipping in and makes for much easier, cleaner use. It's a separate purchase, but it gives you the flexibility to choose the right liner strength and size for your specific outdoor waste.