During the config, the file name is static.
But, you can always create your own microflow when downloading the file in which you modify the file name, or modify the existing one for example to append a timestamp to the filename.
I don't know what your set up is for this is, but if you use a microflow to generate your system file document(preferribly a inheritence) and then create the excel document using the GenerateExcelDOC java action you can set the file name by editing the 'name' attribute of your system file document entity.
Does this work for you?
And what about for concatenate static and dynamic file name?, for example:
I'd like to be:
'Report of' & $Core/Contenedor
concatenate('Report of', $Core/Contenedor)