PHP 7.3 reaches end of support in December 2021 and Adobe Commerce 2.3.x reaches end of support in April 2022. You may want to consider planning your upgrade now to Adobe Commerce 2.4.x and PHP 7.4.x to help maintain PCI compliance.
SwaggerWebapi
The Magento_SwaggerWebapi module provides the implementation of the REST Webapi module with Magento_Swagger.