What you can do is:

Instead writing icon as a string value, you can pass the icon name which are importing from @fortawesome/free-solid-svg-icons.

So your code should look like:

{
  icon: faFax, // icon name not string
  topic: "Our Location",
  content: ["SoHo 94 Broadway St New York, NY 1001"]
}

Here is the working solution of your problem:

import {
    faMapMarkerAlt,
    faPhoneAlt,
    faEnvelope,
    faFax
} from '@fortawesome/free-solid-svg-icons'
import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
import React from 'react'

const ContactTopForm = () => {

    const contactInfoTop = [
        {
            icon: faMapMarkerAlt,
            topic: "Our Location",
            content: ["SoHo 94 Broadway St New York, NY 1001"]
        },
        {
            icon: faPhoneAlt,
            topic: "Phone Number",
            content: ["+254 700 000 000", "+254 700 000 000"]
        },
        {
            icon: faEnvelope,
            topic: "Our Emails",
            content: ["email1@mail.com", "email2@mail.com", "email3@mail.com"]
        },
        {
            icon: faFax,
            topic: "Our Location",
            content: ["SoHo 94 Broadway St New York, NY 1001"]
        }
    ]

    return (
        <div className="contact-form-top">
            <div className="contact-form-top-content">
                {contactInfoTop.map((element) => (
                    <div className="contact-form-item">
                        <FontAwesomeIcon
                            icon={element.icon}
                            className="contact-form-icon" />
                        <h4 className="contact-form-item-h4">
                            {element.topic}
                        </h4>
                        <div className="contact-form-item-div">
                            {element.content.map(item => (
                                <p className="contact-form-item-p">
                                    {item}
                                </p>
                            ))}
                        </div>
                    </div>
                ))}
            </div>
        </div>
    )
}

export default ContactTopForm

You can read more in this link.