If you are not the person who created this form, then you can't change the format.
Formatting is done at form generation time on forms, whether normal PDF or Adobe Sign. For more information on Sign field types: https://adobe.ly/3IS5ps9;
And the suggestion given by @Amal., was referring to formatting done at the Acrobat Desktop app level.
Let us know if that clarifies the problem, and if you have further questions, let us know.