Merge two rows in single to in SQL Server

Question

I have data like this:

<table>
  <tr>
    <th>Item_Code</th>
    <th>Size</th>
    <th>Count</th>
  </tr>
  <tr>
    <td>1001</td>
    <td>XL</td>
    <td>10</td>
  </tr>
  <tr>
    <td>1001</td>
    <td>XXL</td>
    <td>5</td>
  </tr>
  <tr>
    <td>1002</td>
    <td>3XL</td>
    <td>3</td>
  </tr>
  <tr>
    <td>1002</td>
    <td>XL</td>
    <td>10</td>
  </tr>
</table

I want result as below

<table>
  <tr>
    <th>Item_Code</th>
    <th>Size</th>
    <th>Count</th>
  </tr>
  <tr>
    <td>1001</td>
    <td>XL,XXL</td>
    <td>15</td>
  </tr>
  <tr>
    <td>1002</td>
    <td>3XL,XL</td>
    <td>13</td>
  </tr>
</table>

I want this thing in SQL Server. Can anyone please help me with this?

I know the query to concatenate the multiple row values into a single column, but I don't know along with other columns also.