I recently bought a new MacBook and it doesn't have a usb port (I knew this when I bought it) I assumed there was a way to sync my iPhone to it wirelessly but I'm not sure if you can, Im just wondering if I'm going to have to buy the extension for the usb?
Are you talking about the MacBook that has exactly one port that handles everything, including power? That actually is a USB port, it just uses a USB type-C connector, which is not what your iPhone cord has.
You will need to buy the USB to USB-C adapter. Virtually 100% of USB devices sold today use the connector before type-C, the one that has been standard for nearly two decades (like the one on your iPhone cord), and so buying the adapter will likely become necessary at some point regardless of your iPhone's need for it.
Once you plug the iPhone into the MacBook for the first time, you can modify the settings so you can sync wirelessly with iTunes in the future - see Tetsujin's answer for instructions.
From comments - you may need to borrow an adapter to initialise the trust between iPhone & Mac, physically [see if a Genius bar will let you borrow one of theirs for 5 mins; they'll probably help you do it, too]
after that it will work as below...
You can sync & backup your iPhone to iTunes, so long as they are both on the same WiFi network.
It will run automatically when the phone is plugged into a charger, or manually at any time by selecting the device, then clicking the Sync button in iTunes.
You can also manually run Backups the same way.
I use these settings so that I get sync to iCloud & iTunes automatically…
Backups go automatically to iCloud & manually to the Mac.
Note both Sync & Backup buttons are active, even though the phone is not currently connected over USB.