@Anonymous Hi Hunter. I took a look at both the pdf and the dwg file. I understand the frustration of those extension lines, but there are several things at play in your drawing and in your graphics hardware and software that can effect the way that overlapping extension lines display, whether on screen or in hardcopies.
You can manually turn off extension lines using the properties palette "Ext line 1" or "Ext line 2", depending on which one is overlapping. However other things like lineweight assignments and layer properties could use some attention so that your drawings have better clarity when plotted (or just viewed). Don't get me wrong, a lot of what I see looks quite good in your drawing already.
I would suggest looking into setting up a standard template that has your preferences "baked" into it such as text styles, layers linetypes, plotting pen assignments annotative features (if you wish to go that route) dimension styles, multi-leader styles and there are even more if you want to continually improve your templates.
Also, you could perhaps try using the Page Setup Manager to modify the Model space tab use the DWG to PDF.pc3, then select PDF Options button to set the Merge control to "Lines Merge" and see if that helps any if you try plot preview.
As a further suggestion I offer these links for some information on getting started with templates and CAD standards that will help you get oriented with the dwg environment and how to set things to your liking.
There has to be something even better out there at the Autodesk University website but I don't have time at the moment to look for much.
Links:
https://www.autodesk.com/autodesk-university/article/Developing-CAD-Standards-Complete-Guide-2019
https://knhttps://knowledge.autodesk.com/support/autocad/learn-explore/caas/CloudHelp/cloudhelp/2019/ENU/AutoCAD-Core/files/GUID-02979F86-385F-4A53-A3FB-7202F1225CDA-htm.htmlowledge.autodesk.com/support/autocad/learn-explore/caas/CloudHelp/cloudhelp/2019/ENU/AutoCAD-Core/files/GUID-02979F86-385F-4A53-A3FB-7202F1225CDA-htm.html
https://knowledge.autodesk.com/support/autocad/learn-explore/caas/CloudHelp/cloudhelp/2018/ENU/AutoCAD-DidYouKnow/files/GUID-BAEB2254-FC45-48FD-96B1-A955FCA1C688-htm.html
Hope this helps
ADN CAD Developer/Operator