Customize a specific form

Hello,

I would like to customize a specific form of my site by changing the patterns of padding, margin, field size, font size … among other features of the form.

But I would like to change only a single form of the site, as if I created a class for a specific form and changed these parameters.

I do not know if I was clear in the explanation, if you could understand … but if possible I would like to know how to do this customization of a specific form.

Thanks in advance and I await contact!