Yes. Ensure the new drives are from same family (SAS or SATA) and same type (HDD or SSD) of existing drive. Once replaced wait till rebuild complete before replacing next drive. Before replacing next drive ensure virtual disk is back online without any errors. Note : It is good practice to backup your data before carrying out any such tasks as there could be unforeseen behavior.
Hi, I'm using a PowerEdge server + H710 PERC controller. I have a RAID 6 consisting of six 3.5" drives. From what I understand from the manual, it's possible to replace the HDDs with larger capacity. I only want to replace the RAID 6 drives. The procedure (again, as I understand) is to swap out one drive at a time and wait for a rebuild of that drive. When all the drives have been rebuilt, I can increase the capacity of the virtual disk. Have I understood that correctly? Is there anything to watch out for?  
H710 PERC upgrading HDDs in a RAID