What should I wear ??

So I have to go to a wake this Saturday for step sisters bestfriend , I’m not sure what to wear it’s going to be very hot I know you shouldn’t wear bright colors or shorts but I was wondering if I could wear a black long sleeve even though it’s going to be hot I can chnage later and wear dark jeans , another outfit was a black tank top and dark jeans again and I will obv be wearing sneakers I dontknow if sandals are appropriate can anyone else give me ideas ?? I’m stressing