Is there an if statement for ansible hosts?

I am trying to pick host depends on --extra-var variable, now the file is in a vars folder.

i tried to search online, but i missed how to do it with Jinja, cuz its not a role with tasks and template, so how can i relate a jinja to any yaml file? so this is a yaml file found in my vars folder which i configure there all of my metadata to configure, and now i am stuck with this one, i know theoretically i need to create a jinja, in there to do the expression and get the out put to there, the problem i cant figure out is how to include jinja into normal yaml file

host: 'kvm1'  ### if -e iscluster=true use kvm2 else keep kvm1
    memory: '2048'
    network_interfaces:
      - source: 'br3'
        network_driver: 'default'
        type: 'bridge'

Thanks in Advance, and sorry if this is stupid but i am sitting on this one for a while