That UI is called VSCode

At the top of your .yaml file, you can set a JSON Schema. Example:

# yaml-language-server: $schema=https://json.schemastore.org/prometheus.json

scrape_configs:
  - job_name: caddy
    static_configs:
      - targets:
          - caddy:2019

This way, you don’t have to memorize every possible setting and what it does and risk making a typo in the config. VSCode will just tell you.