Many factors, I swear some of you guys lol, not you in particular bro, but when I started in this beloved hobby the Internet didn't exist and so I read books at the library, just somewhat amazes me how much people on these forums do not know basics like what t/s parameters mean and ohm's law. The internet is such a huge wealth of free info. Again not trying to single you out bro or be a **** to you.
Anyways do a little research and read some articles/books. Many factors determine box requirements. Mainly t/s parameters, but also what you want the sub to actually do and music type, shit like that. Read some technical articles. JBL has some really interesting and scientific ones. Loudspeaker Cookbook really helped me out back in the mid 90s trying to help myself learn when I really didn't know anything and there was literally nobody to ask. Most of those basics still 100% apply. Do this, read Loudspeaker Cookbook and design a box using t/s parameters, use charts, graphs, paper and pencil. It will give you a new appreciation of the hobby. Just do it and have some fun.