Update iOS before first setup

Set up the phone as a new phone, doing only the minimum necessary to get to the login screen and log in. Then go to Settings/General/Software Update and update the phone. Then reset the phone to factory settings and start over→Restore your iOS device to factory settings - Apple Support

Is it possible to update it via my Macbook before first setup?

No, you need to go through the basic simple setup first (skipping the steps about transferring data).

Then....you can connect the iPhone to the Mac and run the iOS update that way.

When the update is done, erase the phone and start over again with a new setup to include the transfer of data from the Galaxy phone.

You can't. Individual iPhone 13 units may come with different iOS versions; if the one on yours isn't new enough, update it to 16.6, erase it, and set it up again.

(242764)

Why did you both say to Factory Reset the device after updating?

So you can start all over with a new setup and transfer the data from the Galaxy to the new phone....with the up to date iOS version......as part of the setup process.

In other words, you can't transfer the data from the Galaxy to the new phone....and then update the iOS version....because the Galaxy data will not transfer correctly to the older iOS version on the phone before the phone is updated.

Hello dr_aequitas!

Your iPhone 13 can be updated to the latest iOS as of now, which is iOS 16.6.

As you’re not there yet, please tap here to learn how to update your iPhone. 

👉 Updating/upgrading your iPhone 

If your iPhone won’t update, please see: If your iPhone or iPad won't update - Apple Support. 

👉 Updating iOS: common issues and solutions - Apple Community

👉 If you see error 9, 4005, 4013, or 4014 when you restore your iPhone

I hope this is helpful. Good Luck!

Why did you both say to Factory Reset the device after updating?

Because if you don’t then Move to iOS won’t work.

Because the asker wants something which can only be done during setup.

(242765)

Thanks guys! Really appreciate your replies.