I have never ordered frozen food from Amazon nor did I know that it was available. The food is probably shipped in a cooler packed in dry ice.
One time I ordered 100 custom Hershey bars from a small company in the middle of summer in Arizona. The seller packed the bars in a cooler that was stuffed the dry ice. When I got home from work one day the chocolate was waiting on my doorstep. It did not melt even though it was 110+ degrees outside.