If you want to display sort by form/Filter Form in category page, please try go to your admin:Please open the Modules menu >> find ‘Layered navigation block’ module >> Click to Edit this module:

In this module configuration, please edit the ‘filters template’, please see screenshot here:

Then you can select all categories or only select the categories that you want the filter form display there.

I hope this is helpful for you.

Thanks & Best Regards.