Without more context, it is a bit hard to understand that sentence, but I will give it a try.
We're trying to close it as a bigger project.
If the project has not yet started, and people are trying to get approval for it, or funding for it, then closing the project may be read as closing the deal.
So they may mean, in that case, that they are trying to get approval for the said project by classifying it as a "bigger project" - whatever that means in the context. Possibly, whoever they need the approval or funding from, has separate budgets for differently sized projects, and by "upscaling" this project, it may be possible to secure funding.
On the other hand, if the project has started and is currently being executed, closing would indicate that it will be ended. In that case, it does become obscure why it would be ended "as a bigger project".
One possible interpretation would be that closing the project is actually not a negative thing, but describes the project actually being finished well. In that case, the project may have grown beyond its original scope, and by while it originally may have been (seen as) a small project, it actually became quite big.
In order to justify the extra costs and time that that larger scope undoubtedly entailed, it would make sense to redefine the project as larger than it was originally defined.
I can think of something that started as "redesign of the log in page" and ended up as "rewrite of the complete application authentication structure".