Changing mandatory field colorsetting Sharepoint library online

Trying to modify the mandatory field setting. white text in a cream colored field 

I have tried 

https://support.microsoft.com/en-us/office/format-a-column-to-change-how-it-looks-6ed2f787-0e9e-4908-b861-0d06571c256d this changes all columns 

I was not sure what line item was for powershell .  I was looking for text box setting for cream color or font color.

There doesn't seem to be a easy was to change the color of this 

Any help would be great.  thanks