Category Lists

I am hoping for a shortcut. The site I am converting from manual coding to WordPress using GeneratePress Premium is collectorwiz.com and currently has 257 combined Parent/Child Categories. When someone goes to Blogs, or Events or classified... they are able to search 2 ways (via keyword or category) an ONLY those specific categories with information appear. They are not taken to a page that lists anything in that category.

I would like to know if there is a PlugIn or Widget I should be using to place on specific pages so that when people search ... they only get the items within that category for that Page.

Example: Classified Ads ... I do not want news posts, or business ads showing up when someone selects a specific Category to search classified ads.

I am currently trying to set things up via WordPress/ Elementor Pro/ GeneratePress Premium at https://www.collectorflip.com

I was told by WPLive that I would need to set up a category list for each different page... is that true? I was hoping to be able to copy that same category info on specific pages.

Please advise if there is an easy way to do this... thanks a bunch
Susan Maczik