if you mean to allocate more space on existing disk: How do I change values like wallet address or storage capacity? | Storj Docs
If you mean to migrate to a bigger disk: How to migrate the Windows GUI node from one physical location to another? | Storj Docs
If you mean to add a new disk, then the short answer is “no”. You need to setup a second node with a new generated identity (and a new name) and either setup it with a docker (supported by Storj) or with Win GUI Storj Node Toolbox (supported by the Community).
See How to add an additional drive? | Storj Docs
The longer answer - you can add a new drive to the same node, if you would use a Windows Spaces or RAID, but it requires moving all data to somewhere, the online conversion is not possible. Moreover - you need to create a virtual disk with parity, otherwise with one disk failure the whole node is lost, so you need to have at least two new disks with the same size (in most RAID systems) as a first one, the minimum amount of disks for RAID5 (Windows Spaces with parity) is three disks, and one disk will be wasted for parity.
Using RAID5 with todays disks is very dangerous - you can lost a whole array during rebuild because of bitrot after the one disk failure. So, you need to use at least RAID6 (can survive two disk failures) or RAID10, but you will waste two disks for parity instead of one in case of RAID5.
So, if you want to add only one disk - then start a new node on it. Two nodes in the same subnet /24 of public IPs will receive the same amount of data as a one node, so you will have a RAID on the network level. If the one node is lost - you will lose only that part of common data, not a whole dataset.
See also RAID vs No RAID choice