I’m trying to fetch rows based on the "created_at" field that are older than (for example) 30 days

I’m trying to fetch rows based on the created_at field that are older than (for example) 30 days.

I’m using Laravel Eloquent. Can somebody help me with this?

I want to change the text in crud to be red here is my code

public function   get_list_credit(Request $request) {$resultat=tbl_depot::whereEtatservi('Etatservi'== 0)
->orderBy('id','DESC')->get();

if('created_at' >= Carbon::now()){

}else{

}
return response()->json(['data'=>\$resultat ]);
}


Source: Laravel