In Borderlands 3 the Mayor costume is a unique outfit added to the game along with the release of Moxxi’s Heist of the Handsome Jackpot add-on. To get it, you need to collect all the pieces of clothing scattered around. Their search allows you to perform one of the crew’s trials and get the outfit achievement.
All elements of the suit can be found while performing a new quest chain, freely exploring additional locations. To see how many pieces you have already found, press L3/Left stick on the world map and right button on D-Pad to open the ” Challenges” tab.
On the world map, those items that you haven’t found yet are marked with a green claptrap icon, and those that you have found are marked with a blue (slightly transparent) icon. You can collect them in any order, playing for any hero you like. Just visit the right location, defeat the enemies that may appear there, and pick up the thing.
How to complete the Mayor’s costume in Borderlands 3
The first part of the Mayor’s costume
Area: The Spendopticon.

The second part of the Mayor’s costume
Area: The Spendopticon.

The third part of the Mayor’s costume
Scope: Impound Deluxe.

The fourth part of the Mayor’s costume
Area: The Compactor.

The fifth part of the Mayor’s costume
Region: VIP Tower.

These are all the places where you can find parts of the Mayor’s suit. As soon as you pick them up, you’ll have the Killer Outfit achievement right away.