The logs found in: C:\Program Files\Microsoft\Exchange Server\V15\Mailbox\Mailbox Database
Are these used to support the indexing or something important? I only ask because they take up a chunk of space and if they're just used for error/warning logging I was wondering if it was possible cut down on them through a setting I'm unaware of?
Those are the Exchange transaction logs. They are necessary for the proper operation of the mailbox database. The way to "cut them down" is to perform a Full backup of the Information Store with an Exchange aware backup program (like Windows Server Backup) that can flush the transaction logs, which will delete the transaction logs that have been committed to the mailbox database.
An alternate way of "cutting them down" would be to enable circular logging on the mailbox database, as long as you understand the implications of doing so.