The current .NET version on our WorldServer 11.8.3 environment is 6.0.10. We've been informed that we should upgrade to a higher .NET version due to the end of support for .NET 6 on Nov 12 ,2024. Is a higher .NET version compatible with our WorldServer version (11.8.3)?

Please note that the end of support from Microsoft for version NET 6.0 does not mean that this version is a security risk.

Microsoft .NET Runtime 6.0 and Microsoft ASP.NET Core Runtime 6.0 are system requirements for the  File Type Support (FTS) Server, as documented here.

Your current version of WorldServer needs .NET 6 to run the  File Type Support (FTS) Server and Online Editor. So, you won't be able to update it to a higher .NET version at this point.
However: you can upgrade to a major patch of the same .NET Core 6, i.e. 6.0.X.

We will release the next version of WorldServer (11.8.4) around the end of April 2025. This version will support .NET 8.