> Is it possible for me to update my hosts to the newste ESXI version in vSphere?
Without details the answer is an easy YES.
To get a good or helpful answer details are required.
Are the ESXi hosts being managed by a vCenter Server?
What version of vCenter Server and ESXi are you using?
What version of vCenter Server and ESXi do you want to use?
Do you have an active support contract?