Outfits, and what the style packs tell you
Two paid wardrobes, one modern and one period. Between them they show more of the clothing system than Rockstar has described.

Rockstar has not explained the clothing system, but it has photographed a great deal of it, because two of the paid packs are largely wardrobes.
The Ultimate Edition carries a set called Vice City Style, shown across five images on both leads. The Vintage Vice City Pack pre-order bonus adds a set of period looks alongside the '55 Vapid Stanier.
The modern set
Loose patterned shirts, linen, tiger-print boots, cropped jackets and a lot of unstructured tailoring. It is beach money rather than office money, which is the correct read on the city.

What is notable is that the outfits are shot as outfits, styled head to toe on both characters, rather than as a grid of individual garments. Rockstar is presenting looks, not inventory.
The period set
The Vintage pack goes somewhere different. Sequinned red, wide lapels, feathered hair, blue eyeshadow, and a couple photographed outside the Ocean View Hotel in full eighties dress.

This is the pack doing something clever. Grand Theft Auto: Vice City was set in 1986. Selling eighties clothing for a modern-day game lets people dress as the old game inside the new one, without Rockstar having to build a period setting.

What it implies about the system
Three things are visible without Rockstar saying a word.
- Layering exists. Shirts open over vests, jackets over cropped tops, and shirts tied at the waist all appear across the sets.
- Both characters share the system. Every pack is shown on Jason and Lucia, so this is not a Lucia-only feature.
- Branded in-world clothing is a category. Goodtime Gear appears as its own labelled item, worn in front of a Vice City mural, which is the series' long habit of selling you a shirt for a fictional company.

The part that actually matters mechanically
Your clothing is a tracked item in the evidence system. The police build a description from what you were wearing, and changing clothes invalidates it.
That turns a wardrobe from decoration into equipment. A distinctive outfit is a liability during a job and an asset afterwards, and having more than one set of clothes stops being a cosmetic choice.
Whether the game models that at the level of individual garments or a single outfit slot has not been shown.
What is not known
Rockstar has not described the clothing system, named any stores beyond Goodtime Gear, or said whether outfits can be saved as sets. Everything above is read off photographs of paid content.
Related: tattoos, hair and clothing.
