I conducted some experiments after I died to the wither in full protection 4 netherite armor in my survival world. use "/effect give" to give myself the wither 2 effect for 10000 seconds, and test how long it takes to kill me with protection enchanted armor and with no armor. in bedrock edition the enchantments made no difference, which I found strange because I had a much easier time defeating the wither in 1.15. I then did the same experiment in java, and found out it took significantly longer for the character to die when wearing a full set of protection armor.