If I'm understanding correctly, I believe you can use a BulkAttributeRenamer with the parameter shown in the screenshot.

No, sorry. I was updated the post. It´s better to understand.

Do you mean something like this:

Create a new attribute named with the value of anoher attribute:

You may be looking for AttributePivoter, that performs a grouping of values in a single column, and aggregates the other values.

Very good!

But the new attribute created don´t exposed automatically. It´s a problem.

This is stepping into dynamic workflows/schemas. You now need to create a schema feature with the correct schema and change your writer to accept a schema feature. Ofcourse, if you're wanting to use FME transformers after setting that new field it becomes problematic, but there are ways around it depending what you're wanting to achieve

https://community.safe.com/s/article/dynamic-workflow-tutorial-introduction

https://community.safe.com/s/article/dynamic-workflows-advanced-example-modifying-the-s