Sandals with socks...
No, please no, God no...
Here where I live in Switzerland, especially in the German speaking part, it's perfectly acceptable among the older generation to wear dark brown leather sandals with brown or black socks.
At the school where I work, the rector (principal) frequently wore a somewhat cheap blue looking suit with brown leather sandals and brown socks.
Yes, he wore this outfit even to formal events, perhaps especially to formal events.
Thankfully, he has since retired.
Of course, the younger generation is coming up with skinny jeans, luxury remakes of eighties tennis shoes, and no socks.
You can't win. Then again, to each his or her own.
Footwear is a broad church. Let us all worship as we will.