Yes, Visio online, or Microsoft Visio Online, comes with Office 365 subscription, but only has viewing and sharing capabilities, and no edit/create rights. Therefore, you cannot generate flow charts, or create drawings, with it, and for that, you need to buy Visio Online subscription to acquire the rights.
Planning to become a Business Analyst? Enroll in Intellipaat’s Business Analyst course, which offers you with an industry-grade course that will enhance your hands-on experience, and practical skills. Also, if you are a beginner, check out the following YouTube video on Microsoft Visio Tutorial and get started.