How to create a fixed-width file

We have the need to generate files with a fixed-width data format. Has anyone figured out how to do this from a Power Automate Cloud Flow? I'm able to create a CSV files, but not seeing any actions for fixed-width. Do I need to create a CSV and write something else to convert it?

I know this is an old post, but I want to provide steps to do this within a cloud flow in case anyone else views this question like I did. My use case involved sending data from a SharePoint list via SFTP in a fixed-width text format. I had 64 columns and around 1,000 rows of data to process into a flat file with specified lengths and starting positions for each field. Some fields required transformation via expressions, some were hardcoded, and a couple didn't exist on our list but had to be included to maintain the required file structure. This was daily scheduled process that took around 30 minutes.

The overall flow:

Apply to each snippet:

Each Compose action corresponds to a required field in the flat file, using a consistent expression structure. Below is an example. this expression concatenates the value of field_10 (my list's internal name for 'US State') from the current item in the "Apply to each" loop with two spaces, then extracts the first two characters of the resulting string. You just need to change the dynamic value for the field, the padding, and the number of characters based on your length requirement for each specific field. This ensures that each field will always meet the specified length requirement, regardless of whether it contains data--fields that didn't exist in my list would simply have a blank value ('') in place of the dynamic content.

substring(
    concat(items('Apply_to_each')?['field_10'],
        '  '
    ),
    0,
    2
)

The 'Compose concatenated fields' action does as implied, concatenating the fields in the required order.

Below is a generic example.

concat(
    outputs('Compose_Field1'),
    outputs('Compose_Field2'),
    outputs('Compose_Field3'),
    outputs('Compose_Field4'),
    outputs('Compose_Field5')
)