core/homeassistant/components/logger/services.yaml

set_default_level:
  description: Set the default log level for components.
  fields:
    level:
      description: "Default severity level. Possible values are debug, info, warn, warning, error, fatal, critical"
      example: debug

set_level:
  description: Set log level for components.
  fields:
    homeassistant.core:
      description: "Example on how to change the logging level for a Home Assistant core components. Possible values are debug, info, warn, warning, error, fatal, critical"
      example: debug
    homeassistant.components.mqtt:
      description: "Example on how to change the logging level for an Integration. Possible values are debug, info, warn, warning, error, fatal, critical"
      example: warning
    custom_components.my_integration:
      description: "Example on how to change the logging level for a Custom Integration. Possible values are debug, info, warn, warning, error, fatal, critical"
      example: debug
    aiohttp:
      description: "Example on how to change the logging level for a Python module. Possible values are debug, info, warn, warning, error, fatal, critical"
      example: error