Drupal - How to rename column of a content type

Introduction

You already have a content type with one or more fields in it. Later, you realize you should rename it due to whatever reason. Lets take an example:

A text field(long text area)
Image field

Drupal provides no way to rename existing fields of a content type. But, you can do this programatically or by a db query.

Programmatic Solution

Do following steps:

Add the fields into your content type, with the name you want
See below php code for drupal

$query = db_select( 'node', 'n' );
  $query
    ->condition( 'n.type', 'article' )
    ->fields('n', array('nid'));
  $result = $query
     ->execute()
   ->fetchAll();

  foreach( $result as $row ) {
    $nd = Drupal\node\Entity\Node::load($row->nid);
  
    $nd->body = $nd->field_article_introduction;
    $nd->field_image = $nd->field_top_image;
    $nd->save();
  }

The idea is to fetch all such nodes for that particular content type, and assign old values to the new fields you just created.

You can put multiple fields if you have in the php code above.
Make sure you have copied content, by loading one or two nodes
Find out all the views you have created wiht old fields. You need to put new fields with same settings.
Find out the occurrences of those old fields in your custom theme code.
Now, delete old fields from your content type

Clear the cache and test it.