This guide will tell you how you can get Free Extra Gucci Bag in Roblox Project Jojo. Also, which quest you have to complete the get a free extra bag.
The first thing you have to do is go to Rohan and have a chat with him. 
Your first quest is: Find zeppli and get hamon. 
Now you need to kill DIO (with any stand). 
After that, you need to get DIO’s Diary for him. 
Now for the last quest, you need to kill Kira.
And then, you have the free Extra Storage. 
Press L to open and K to Store/withdraw. 