A vSphere Essentials license entitles you to three 2-socket ESXi hosts and a vCenter licensed for Essentials. At your second site, you could only join max of 3 hosts to that vCenter licensed for Essentials, so it's seems like it would be pointless if you have to buy a second Essentials kit anyhow.
It is my understanding is that you need another instance on vCenter at the remote site to enable replication..That would be the reason I would look to acquire it by getting a standard Essentials Kit. I am not aware of vCenter Essentials being available alone
Welcome to the Community,
although you may be able to make this work from a technical point of view, such a configuration would violate the licence agreement, because an Essentials Kits may only be used as-is, i.e. parts may not be decoupled and/or used other kits/solutions.
As additional note.... vSphere Replication comes with Essentials Plus and above and its not part of the "basic" vSphere Essentials.