Is there any field available in journey with which I can check if user has unsubscribed an email? Do I need to create the field manually?
You would need query the fields SubscriberKey and Status from _Subscriber and add it to a data extension (let's call it StatusFromSubscribers). Then in data designer you connect StatusFromSubscribers with your sendable data extension which you would need to use as entry source for your journey. You can then apply a filter based on the field Status from StatusFromSubscribers.