Removed the end caps, but can't read the size w/o removing the bearings since the red side doesn't have any text on it.
Note that the post refers to cartridge bearings, rather than loose balls for cup and cone bearings. The code could be on the inboard seal, but that means you have to remove the bearing to see it. In this situation, there may be a few ways to get at the code.
First way could be to browse their service manuals. Here is one manual that I believe is for 2016/2017 model year wheels and hubs. Unfortunately, the manual says that you should call a DT Swiss dealer. There is a code laser etched on the hub that would identify the parts necessary. The manual said that there were too many permutations of parts to be certain. This manual for 2015/2016 hubs didn’t give bearing sizes either.
You could see if you can get calipers into the hub. You want to measure the bearing’s external diameter, its internal diameter, and its depth. If you then searched for those 3 numbers, you’d know what bearing to get. For example, inner diameter of 15mm, outer diameter of 28mm, and depth of 7mm mean that it’s a 6902 bearing, which is quite a common size.
You could also Google. To do this, it would help if you know what level of hub your wheel has. I think one review of this wheelset mentioned ratchets, and given the price point, that should mean 350 level hubs (whereas 370s have pawls). The bearings might differ depending on if the hub is rim or disc brake, and 6 bolt vs centerlock, so you’d need to be careful with this.