Dump the configuration for a Symfony extension

./bin/console debug:config <bundle-name>

For example:

./bin/console debug:config ApiPlatformBundle

shows:

api_platform:
    mapping:
        paths:
            - /Users/sajad/code/symfony/bookshop-api/src/Entity
    patch_formats:
        json:
            mime_types:
                - application/merge-patch+json
    swagger:
        versions:
            - 3
        api_keys: {  }
    title: ''
    description: ''
    version: 0.0.0
    show_webby: true
    default_operation_path_resolver: api_platform.operation_path_resolver.underscore
    name_converter: null
    asset_package: null
    path_segment_name_generator: api_platform.path_segment_name_generator.underscore
    allow_plain_identifiers: false
    validator:
        serialize_payload_fields: {  }
    eager_loading:
        enabled: true
        fetch_partial: false
        max_joins: 30
        force_eager: true
    enable_fos_user: false
    enable_nelmio_api_doc: false
    enable_swagger: true
    enable_swagger_ui: true
    enable_re_doc: true
// etc...

You can also view configuration at a specific path. For example:

./bin/console debug:config api_platform collection.pagination