When my Dad golfed in the winter (like orange golf balls and three feet of snow), he wore pantyhose under his thermals. My mom actually modified them with a fly.
Now he chose the black ones so as not to be too prissy, but he was VERY confident in his manhood. He did it to keep warm, not look better.
I like silk long johns, and they'd work under thermals for those really bad sub zero days. They come with the fly by design. L.L.Bean and Dicks sells them. Very warm and comfortable, even sitting in a duck blind.
Your dad may want to check out UnderArmour. They’re pricey but really warm.
That goes without saying. He was golfing...
...like this happy couple:
"looking better" is the antithesis of golf.
In fact, it would be doing a public service to make that couple look better, by removing those horrid 'glad rags'.