How do I label and use anchors?

Probably this is what You looking for:

.number: &AnchorDelay
    optimistic: true
    min_value: 0
    max_value: 600
    step: 1
    initial_value: 0
    web_server: &AnchorDelayWebServer
      sorting_group_id: sorting_group_switchmain
      sorting_weight: 30

number:
  - platform: template
    <<: *AnchorDelay
    id: "SwitchMainDelay"
    name: "Main Switch Delay"

  - platform: template
    <<: *AnchorDelay
    id: "Switch01Delay"
    name: "Switch 01 Delay"
    web_server:
      << : *AnchorDelayWebServer
      sorting_group_id: sorting_group_switch1

  - platform: template
    <<: *AnchorDelay
    id: "Switch02Delay"
    name: "Switch 2 Delay"
    web_server:
      << : *AnchorDelayWebServer
      sorting_group_id: sorting_group_switch2