Try putting Vicks vapor rub in their feet then cover with socks. Helped when my daughter had her first big cold. But remember to wash it off before going outside!

Saline drops help loosen it up a bit

We had a humidifier and used it at night. He sounded a lot better in the morning

Those two things work but they take time. Poor baby may have to suffer through. Tried the honey cough syrup didn't work.