Even though Enterprise users can purchase an Extended Security Update on an expensive yearly plan, it is highly advisable to upgrade to Windows 10 as soon as possible.

For customers who are unable to do so at the moment, Sophos continues to offer support for their endpoint protection services on computers running Windows 7. Support for on-premise appliances is live until the 31st of December 2020, and for cloud-managed solutions until the 30th of June 2021.

Please consult the Sophos Knowledge Base article below for information on supported platforms and the retirement calendar of Sophos Endpoint and Server Protection.
https://community.sophos.com/kb/en-us/119018

A comprehensive, cloud-managed endpoint security solution, using a sophisticated type of machine learning, Sophos Intercept X provides protection against both known and unknown threats. Intercept X with EDR is also available for endpoints and servers.
https://www.sophos.com/en-us/products/intercept-x.aspx
https://www.sophos.com/en-us/products/server-security.aspx

Further information on Sophos endpoint protection solutions can be found here:
https://www.sophos.com/en-us/medialibrary/PDFs/factsheets/Sophos-Endpoint-dsna.pdf