Deployment supports not only the equality-based selector, but also the set-based selector, to specify ReplicaSet. To do that, you can write spec.selector.matchExpressions[] to specify the key and in/notin operator. For example, if you want to specify project in (poc), environment in (staging), tier notn (backend,cache), then matchExpressions would be as follows:

$ cat deploy_set_selector.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  replicas: 3
  selector:
    matchExpressions:
      - {key: project, operator: In, values: [poc]}
      - {key: environment, operator: In, values: [staging]}
      - {key: tier, operator: NotIn, values: [backend,cache]}
  template:
    metadata:
      labels:
        project: poc
        environment: staging
        tier: frontend
    spec:
      containers:
      - name: my-nginx
        image: nginx
        ports:
        - containerPort: 80

As you can see, the YAML array is represented as -, and the map object as {}, to specify the key, operator, and values. Note that values would also be an array, so use the square bracket [] to specify one or more values.

One thing you need to aware of is one label, called the pod-template-hash label, which is created by Deployment. When you create a Deployment, it will also create a ReplicaSet object. At this time, Deployment will also assign the pod-template-hash label to the ReplicaSet. Let's see how it works:

$ kubectl create -f deploy_set_selector.yaml
deployment.apps "my-nginx" created

$ kubectl get rs
NAME                  DESIRED   CURRENT   READY     AGE
my-nginx2-764d7cfff   3         3         3         19s

$ kubectl describe rs my-nginx2-764d7cfff
Name:           my-nginx2-764d7cfff
Namespace:      default
Selector:       environment in (staging),pod-template-hash=320837999,project in (poc),tier notin (backend,cache)
...
...
Pod Template:
  Labels:  environment=staging
           pod-template-hash=320837999
           project=poc
           tier=frontend
...
...

As you can see, the ReplicaSet my-nginx2-764d7cfff has an equality-based selector, as pod-template-hash=320837999 is appended to the Selector and Pod template. It will be used to generate a ReplicaSet and Pod name with a particular hash function (for example, my-nginx2-764d7cfff).