Hi. Sorry if this has been answered somewhere else but I am looking into upgrading my leased iPhone 7 on a my flex plan to the iPhone XS. If I pre order the iPhone online, will I be able to send my iPhone 7 back when my new phone arrives or do I need to pre order at an Optus store?
The flex upgrade process is fairly fixed. It involves a third party I believe. Pre Ordering is probably not an option for you.
Note that when you upgrade from a $500 device to a $2000 device you will need to pay the difference in monthly plans.
I'd also suggest a leased plan is risky. It saves a few $ a month but if your phone is lost, damaged or stolen then you'll need to pay to replace it when your contract expires. Make sure its insured on a lease. If its not lost then you have to give back $1200 worth of phone back to Optus (having saved $200 in fees) instead of being able to sell it on eBay for that tidy sum.