Does it mean that I don't have to Shutdown Guest OS to perform this type of changes?
Yes, you don't need shutodown the guest and/or host.
Just check this recommendation from VMware:
Note: If the LUN experiences a high I/O throughput when growing the VMFS, the ESX host may not be able to complete the operation. In such a case, repeat the process during non-business hours and when backup operations are not running. If the problem persists, power off some of the virtual machines residing on the LUN and then retry.
Source: VMware KB: Growing or expanding a VMFS volume or datastore