The Diablo 4 transmog device can be accessed thru the Wardrobe, that's found within the Kyovashad hotel. You'll go to this metropolis early within the campaign. Anyway, given that Kyovashad is the principle hub within the Fractured Peaks, it will have this specific feature, though you might additionally see it somewhere else whilst you get to D4 items go to the hubs/principal towns in future acts.
As for the designs of each weapon and armor, you may not have access to these by means of default. Instead, you will need to go to the Blacksmith. When you mouse over an object, it have to say "unlocks new appearance on salvage," at the side of a pickaxe icon. These denote that salvaging those gear portions could permanently keep their layout for use in transmogrification.
Anyway, lower back to the Diablo four transmog system and Wardrobe. You'll observe the Appearance tab, that is comparable to man or woman creation in which you modified your person's face and markings, in addition to the Wardrobe tab, which is RPGAH.COM in which we will make some cosmetic tweaks. Here's the gist: