Will using the condition Ticket: Description | Contains the following string/word, in an automation pull ticket subject text?
No, while triggers can be fired based on subject data, automations cannot.
A workaround to this can be accomplished by creating a trigger to automatically tag tickets based on ticket subject data. You can then use the ticket tag added by the trigger to create an automation to fire on the ticket.
For more information, see the article: How do I create a trigger based on a ticket subject?