Expand and Collapse feature in PowerApps

Write the following on APP Start Code:

 Clear(colTreeElement);  

 ForAll(
   TreeViewElement,
   Collect(
     colTreeElement,
     {
       ElmntName: Switch(
         'Element Name',
         "India",
         Concatenate(
           "India",
           "                                     ",
           "Score:4"
         ),
         "United States",
         Concatenate(
           "United States",
           "                             ",
           "Score:8"
         ),
         'Element Name'
       ),
       ElmntId: 'Element Id',
       Lv: Level,
       ParentId: 'Parent ID',
       //Add column 'Show' to control Expand/ Collapse
       Show: If(
         Value(Level) = 1,
         true,//only the element with spElmntLv = 1 is displayed in the initial state
         false
       ),
       TreePath: ""//Treepath is defined as
     }
   )
 );
 // Define TreePath
 UpdateIf (
   colTreeElement,
   Value(Lv) = 1,
   {TreePath: ElmntId},
   Value(Lv) = 2,
   {
     TreePath: Concatenate(
       ParentId,
       ">",
       ElmntId
     )
   },
   Value(Lv) = 3,
   {
     TreePath: 
   // Lv3 TreePath uses spParentID of the record (own parent record) where own ParendId and spElmntID of original data source match
 Concatenate (
       LookUp (
         TreeViewElement,
         'Element Id' = ParentId,
         'Parent ID'
       ),
       ">",
       ParentId,
       ">",
       ElmntId
     )
   },
   Value(Lv) = 4,
   {
     TreePath: 
   // TreePath of Lv4 uses spParentID of the record (the parent record of own parent) where spParentID obtained by Lv3 procedure and spElmntID of the original data source match
 Concatenate (
       LookUp (
         TreeViewElement,
         'Element Id' = LookUp (
           TreeViewElement,
           'Element Id' = ParentId,
           'Parent ID'
         ),
         'Parent ID'
       ),
       ">",
       LookUp (
         TreeViewElement,
         'Element Id' = ParentId,
         'Parent ID'
       ),
       ">",
       ParentId,
       ">",
       ElmntId
     )
   }
 ) 

Step 1: Add a gallery and add below on 'items';

SortByColumns(Filter(colTreeElement,Show=true),"TreePath",Ascending)

Step 2: Add one image (which will be icon image for collapse/ expand/ bullet point for rows) inside gallery and write below codes on its 'image'. (Note; Collapse, Expand and Radio Button' in the below code is the name of media for collapse, expand icon and radio button icon respectively)

 If(  

   CountRows(
     Filter(
       colTreeElement,
       ParentId = ThisItem.ElmntId
     )
   ) = 0,
   'Radio Button',
   LookUp(
     colTreeElement,
     ParentId = ThisItem.ElmntId
   ).Show = true,
   Collapse,
   Expand
 )

Write below code on 'OnSelect' of image:

 If(  

   //Determine if records with own ID as Parent ID are not 0 and they are displayed
   CountRows(
     Filter(
       colTreeElement,
       ParentId = ThisItem.ElmntId
     )
   ) <> 0 && LookUp(
     colTreeElement,
     ParentId = ThisItem.ElmntId
   ).Show = true,
   //If Displayed, hide all columns that have their ID in the TreePath and redisplay themselves
   UpdateIf(
     colTreeElement,
     CountRows(
       Filter(
         Split(
           TreePath,
           ">"
         ),
         ParentId = ThisItem.ElmntId
       )
     ) <> 0,
     {Show: false}
   );
   UpdateIf(
     colTreeElement,
     ElmntId = ThisItem.ElmntId,
     {Show: true}
   ),
   //If Not Displayed, display the element that has you as the parent (the element immediately below)
   UpdateIf(
     colTreeElement,
     ParentId = ThisItem.ElmntId,
     {Show: !Show}
   )
 ) 

Step 3: Add 1 label inside gallery to display row values and write "ThisItem.ElmntName" on it's text.

Below is the raw data and how it was all configured. FYI colTreeElement is the table name, it'll be different in case of yours when you will add data source of gallery.

Element Name	Element Id	Parent ID	Parent Name	Level
India	1			1
Bihar	2	1	India	2
Gujarat	3	1	India	2
Haryana	4	1	India	2
Karnataka	5	1	India	2
Patna	6	2	Bihar	3
Gaya	7	2	Bihar	3
Muzaffarpur	8	2	Bihar	3
Bhagalpur	9	2	Bihar	3
Purnea	10	2	Bihar	3
Ahmedabad	11	3	Gujarat	3
Surat	12	3	Gujarat	3
Vadodara	13	3	Gujarat	3
Gandinagar	14	3	Gujarat	3
Bharuch	15	3	Gujarat	3
Gurgaon	11	4	Haryana	3
Faridabad	12	4	Haryana	3
Ambala	13	4	Haryana	3
Hisar	14	4	Haryana	3
Rohtak	15	4	Haryana	3
Bangalore	11	5	Karnataka	3
Mysore	12	5	Karnataka	3
Belgaum	13	5	Karnataka	3
Bellary	14	5	Karnataka	3
Mangalore	15	5	Karnataka	3
United States	16			1
California	17	16	United States	2
Florida	18	16	United States	2
Texas	19	16	United States	2
Hawaii	20	16	United States	2
Los Angeles	21	17	California	3
San Diego	22	17	California	3
San Francisco	23	17	California	3
Oakland	24	17	California	3
Riverside	25	17	California	3
Miami	26	18	Florida	3
Orlando	27	18	Florida	3
Pensacola	28	18	Florida	3
Jacksonville	29	18	Florida	3
Tampa	30	18	Florida	3
Houston	31	19	Texas	3
Dallas	32	19	Texas	3
San Antonio	33	19	Texas	3
El Paso	34	19	Texas	3
Brownsville	35	19	Texas	3
Honolulu	36	20	Hawaii	3
Hilo	37	20	Hawaii	3
Kaholui	38	20	Hawaii	3
Lihue	39	20	Hawaii	3
Lanai City	40	20	Hawaii	3