My experience is mostly with x86, where the answer is a definitive "no"; for ARM, my guess is "likely no" --- it's a RISC, so instruction selection isn't as critical, and all instructions are fixed-width so again there isn't as much flexibility in instruction selection (e.g. in x86 a "xor reg, reg" is the canonical way to zero a register, and explicit loading with a constant 0 is very much discouraged and a few bytes bigger, even compilers know about that now.) That said, I've also seen compilers do ridiculous stupid things which no human ever would.

Cant speak much for x86, but for many older / less common architectures (I can speak for z80) the compilers aren’t as advanced or are missing extensive optimizations.