Our dog has multiple beds, each with a blanket. He tends to prefer the doughnut ones.
The fleece blankets serve as warmth, as well as security — I notice that our dog sleeps more peacefully when his head is mostly covered, maybe because he realizes when I cover him that he’s safe. That happens even when we road trip and I cover him.
We’ve often stayed at dog-friendly hotels with him. Sometimes they offer gift packs for dogs. One of them, a golf resort-type hotel in Florida, included a blanket in their gift pack. It looks like a little baby blanket, so cute. Covered in little colorful embroidered circles. It might actually be a baby blanket.