How can I modify this Search section in lookup?

Hello,

In order to modify this window, you need to create a new module that will expand LookupPage

define("CustomLookupPage", ["LookupPage", "LookupPageViewGenerator", "LookupPageViewModelGenerator",
"ProcessModuleUtilities", "LookupUtilities", "css!LookupPageCSS"],
	function(LookupPage, LookupPageViewGenerator, LookupPageViewModelGenerator, ProcessModuleUtilities) {
		return Ext.define("Terrasoft.configuration.CustomLookupPage", {
			alternateClassName: "Terrasoft.KmGMSLookupPage",
			extend: "Terrasoft.LookupPage",
			gridWrapClasses: ["custom-lookup-control"]
		})
	}
)

However, this is quite a difficult task. We recommend analysing the base methods of LookupPage to see what is their purpose and when they launch.