get_registered_styles_for_block example

                } elseif ( array_key_exists( 'default', $schema['properties'][ $extra_field ] ) ) {
                    $field = $schema['properties'][ $extra_field ]['default'];
                } else {
                    $field = '';
                }
                $data[ $extra_field ] = rest_sanitize_value_from_schema( $field, $schema['properties'][ $extra_field ] );
            }
        }

        if ( rest_is_field_included( 'styles', $fields ) ) {
            $styles         = $this->style_registry->get_registered_styles_for_block( $block_type->name );
            $styles         = array_values( $styles );
            $data['styles'] = wp_parse_args( $styles, $data['styles'] );
            $data['styles'] = array_filter( $data['styles'] );
        }

        $context = ! empty( $request['context'] ) ? $request['context'] : 'view';
        $data    = $this->add_additional_fields_to_object( $data, $request );
        $data    = $this->filter_response_by_context( $data, $context );

        $response = rest_ensure_response( $data );