Depending on whether GDPR functionality is enabled in your account, you can either check the Communication subscriptions section of a contact record, or individual contact properties.
If GDPR functionality is enabled in your account, you can check the Communications subscriptions section of the contact record:
In your HubSpot account, navigate to Contacts > Contacts.
Click the name of the contact.
In the left panel, scroll down to the Communication Subscriptions section.
If the contact has opted out of all communication, it will stated that [Contact name] is subscribed to 0 out of [X] subscriptions.
Otherwise, the Communication Subscriptionssection will show how many subscriptions the contact has opted into with your HubSpot account. You can click View subscriptions to manage individual subscription statuses for the contact.