IMPORTANT: first of all this texturepack requires optifine, but more importantly the build for this copper mech was made by "AverageTunaSandwhich" on youtube, they are a great builder and this link here is the link to the video where they show this build https://youtu.be/-IpEbgZ8I0s
they made this build entirely, all i did was add some lightning rods at the top because i thought it looked neat and of course made this build into a model and slapped it on the iron golem, i will warn you it is a little scuffed or janky if you will but it works

So yes this texture pack turns the iron golem into a giant steampunk hulking copper titan