InfoPath 2013 is still the standard tool for creating and modifying custom forms in SharePoint. Since InfoPath has been discontinued and InfoPath 2013 is the last version, InfoPath is not a part of the Office 2016 suite. But don’t worry, you can continue using InfoPath 2013 even with Office 2016 because InfoPath 2013 has been made available as a standalone download in the Microsoft Download Center. Be aware that the download and use of InfoPath 2013 requires an active Office 365 ProPlus subscription.

Download InfoPath 2013 for Office 365 ProPlus Subscription