You have seen how to create a build definition using the visual designer. A new, alternative approach, which has been available since early 2019, is the use of YAML pipelines. When working with YAML pipelines, you specify your complete build definition in a YAML file and store it in source control, often next to the source code that the build is for.
While both pipeline systems coexist, using YAML pipelines is now the preferred approach for defining pipelines. This means that it is very likely that new features will only surface in YAML pipelines.