Each workflow is the recommended upgrade path while upgrading your vCenter Server 6.5 and 6.7 environment, that contains one or more host profiles with version 6.0, 6.5 and 6.7.
Upgrade Support Matrix
|Upgrade Workflow||vCenter Server||ESXi host||Host Profiles|
|earlier than 5.5 -> 6.0 / 6.5 -> 6.7||Requires an upgrade||Requires an upgrade||Requires an upgrade|
|5.5 -> 6.7||Requires an upgrade||Requires an upgrade||Requires an upgrade|
|6.0 -> 6.7||Requires an upgrade||An optional upgrade||An optional upgrade|
|6.5 -> 7.0||Requires an upgrade||An optional upgrade||An optional upgrade|
|6.7 -> 7.0||Requires an upgrade||An optional upgrade||An optional upgrade|
|earlier than 6.5 -> 6.5 / 6.7 -> 7.0||Requires an upgrade||Requires an upgrade||Requires an upgrade|
|6.5/6.7/7.0 →7.0 Update 3||Requires an upgrade||An optional upgrade
Note: You might need to keep a 7.0 GA host if you want to validate or edit a 7.0 GA host profile.
|An optional upgrade|
vCenter Server and ESXi Version Interoperability
Starting with vSphere 7.0 Update 3, a major-version vCenter Server instance supports any ESXi Update release version of the corresponding major release. That is, a vCenter Server 7.0 Update 3 instance can manage ESXi 6.5, ESXi 6.7, and any Update release of ESXi 7.0.
So, you must upgrade vCenter Server to 7.0 Update 3, if you want to manage ESXi hosts of version 7.0 Update 3 or a later Update release. You must also upgrade vCenter Server to version 7.0 Update 3 if you want to manage a mixed environment of hosts of any ESXi 7.0 Update release version, for example 7.0 GA, 7.0 Update 1, or 7.0 Update 2.