Dear Johnny Clapham,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
As per your description, it seems that you are trying to do quick search on PowerPoint for Mac to access settings as PowerPoint for web app does, however, not showing the setting as expected in PowerPoint for Mac.
If the understanding above is right, we've also done a quick test in PowerPoint for Mac in version 16.77, and we can reproduce a similar situation on our side, below attached are the screenshot of our test for your reference:
PowerPoint for the web:

PowerPoint for Mac:

As far as we know, there are still differences between PowerPoint for the web in browser and PowerPoint for Mac. Personally, I completely agree with you, it would be definitely ideal if we can search for the settings in PowerPoint for Mac, this is indeed a good addition to the current experience.
Given this, we'd sincerely recommend you share your valuable feedback via PowerPoint > Help > Feedback within PowerPoint for Mac. Feedback submit by this way directly goes to the related team, this is the best way to let PowerPoint developers know your requirements and comments, help improve the product and make it better for you and others.
For your reference: How do I give feedback on Microsoft 365? - Microsoft Support
Meanwhile, please also considering sharing your feedback in PowerPoint Feedback Community (microsoft.com). The Product Team is in-charge of the feedback site, and they are constantly checking the comments and feedback from our customer. Many features have been developed or improved based on users' comment.
Sorry for the inconvenience again. Your patience and understanding are highly appreciated. Hope you stay safe and healthy.
Sincerely,
Rhoda | Microsoft Community Moderator