It depends on when the system was ordered, and how it was originally spec'ed. The 1000W PSU only became available to order on the R13 in early March, 2022...and even then, the option was only available in the higher end spec systems. I know because I originally ordered my R13 in Feb, 2022. At that point, the only PSU available was the 750W. When the 1000W PSU became available to order in March, 2022, I cancelled my original order and reordered with the 1000W PSU. If the system was ordered with the RTX3090Ti, it can only be ordered with the 1000W PSU. So, if your system was ordered prior to March, 2022 it can only have the 750W PSU, and if it has a 3090Ti it can only have the 1000W PSU. Those are a couple of ways to check. Also, if you use the service tag on the support site, you should be able to see what PSU is installed. Finally, if you have access to the packing list that shipped with the system, it will also have the build information. There may be other ways short of physically looking at it that I'm not thinking of, but these will work.
Without physically removing the power supply and checking, is there an option to check whether it is 750w or 1000w? 
Aurora R13, check power supply wattage?