You might be able to do it just by changing you netmask and DHCP range.

Say your router doing DHCP is on IP address 192.168.1.1 and the netmask is 255.255.255.0

That means that there are 253 addresses available, 256 - 1 for router - 1 for network (192.168.0.0) - 1 for broadcast (192.168.1.255).

If you just change the netmask to 255.255.0.0 you will suddenly have 256 times as many addresses. Your address range will run from 192.168.0.1 to 192.168.255.255

What you then need to do is extend the DHCP range

There are other ways of doing it, you could use the Unifi to split the congregation onto a different VLAN and have that on the 192.168.2.0/24 range, but that involves a router (and network switches) that understand VLANs.