I have an older house I want to install a new shower head.. The pipe stem in sower is a smaller diameter end than modern shower head fittings.. can I get an adapter?

I have an older house I want to install a new shower head..The pipe stem in sower is a smaller diameter end than modern shower head fittings..can I get an adapter?
Shower arms come out of the wall at 1/2". That's the standard size. What size is your shower head? Back to you, Tom