Reviewing AutoCAD 2018 shows the New Save As dropdown for File Type 2018.
See the Autodesk AutoCAD 2018 Help file for reference:
http://help.autodesk.com/view/ACD/2018/ENU/?guid=GUID-C36C0AF2-6925-4E7F-BDAD-F57897D837B2
If a newer version of AutoCAD is unavailable to Save As you can use the DWG Convert tool:
https://knowledge.autodesk.com/support/autocad/learn-explore/caas/sfdcarticles/sfdcarticles/How-to-convert-a-dwg-file-to-a-previous-format.html
Brought to you by Ideate Inc. Technical Support ( www.ideateinc.com )
Source: Autodesk
