Beginning in early 2018, FINRA created the regulatory requirement for broker-dealers to offer their customers the ability to list a “Trusted Contact,” although this information is not required.
According to FINRA:
"While you are not required to provide this information to open an account, it may be a good idea to do so. By choosing to provide this information, you are authorizing the firm to contact such person and disclose information about your account in certain circumstances, including to address possible financial exploitation, and to confirm the specifics of your current contact information, health status, or the identity of any legal guardian, executor, trustee or holder of a power of attorney."
Your trusted contact cannot transact on your behalf in any circumstance. Instead, a trusted contact is simply meant to add another level of protection to your account.