I have several ESXi 6.0U3 hosts running VMs. I am purchasing a new server to run ESXi 7.0U1 and looking to do VM recoveries from backup (Veeam) to this host in the event of a hardware failure.
Is it possible/recommended to recover or migrate from ESXi 6.0U3 to 7.0U1 in a production environment.
It's possible, but keep in mind ESXi 6.0 is out of support, so you should at the least be looking at upgrading to 6.5 in some fashion before thinking about DR capabilities. And then you would consider either replication or simple backup/restore.
Adding the following on top of what daphnissov has already mentioned earlier:
If these hosts are standalone, it should be something you can perform.
If these 6.0 hosts are part of vCenter 6 and you are planning to add the 7.0 host also to same vCenter, it's not a compatible configuration. vCenter needs to be at 7.0 to add 7.0 hosts and vCenter 7.0 does not support 6.0 hosts.