The system reserved and other partitions that are created by Windows must be Primary, otherwise, you cannot boot Windows.
In this article, I'll introduce how to resize primary partition in Windows 10 with Disk Management, and the alternative method when it cannot extend a primary partition. To resize and extend primary partition on Windows 10, the native Disk Management is an option, but not all partition can be resized due to some restrictions. However, whether it is possible and safe depends on the tool your are using. It can't be better if you resize and extend a partition when it runs out of disk space.
