I found the solution for it.
to reach to the edit button hook_entity_access()
is the correct Hook but to provide access to that block content, we first need access to class
Drupal\Core\Access\AccessResult
then to provide access we need to return
AccessResult::allowed()
A complete example where we might want to give access to a block_content would look like this.
Use Drupal\Core\Entity\EntityInterface;
Use Drupal\Core\Session\AccountInterface;
Use Drupal\Core\Access\AccessResult;
function block_user_access_entity_access(EntityInterface $entity, $operation, AccountInterface $account) {
if($entity->getEntityTypeId() == 'block_content'){
return AccessResult::allowed();
}
}