In the US, it’s usually clear which you can split if you’re at a beer distributor. There’s usually a 6-pack price and a per bottle price (sometimes you do have to look around for the tags).
Many grocery stores have a section specifically for singles, often with a “make your own 6 pack” that is cheaper than 6 singles.
Often you can get larger cans (24ish oz) that are explicitly sold as singles (pounders, tall boys, lots of slang for these). These are typically the cheap stuff like Bud light or Foster’s