Magento 2.2.2 – Rename Sort By Options Label

On product listing page, I need to rename the label of Sort by Option Position to Most Popular.

Below are the two files responsible for sorting

\vendor\magento\module-catalog\Block\Product\ProductList\Toolbar.php
\vendor\magento\module-catalog\Model\Config.php

In Toolbar.php you can see

$this->_availableOrder = $this->_catalogConfig->getAttributeUsedForSortByArray();

which in turn calls getAttributeUsedForSortByArray() from Config.php that returns array of available attributes to sort listing collection.

In Config.php it has below function where Position label is given

public function getAttributeUsedForSortByArray()
    {
        $options = ['position' => __('Position')];
        foreach ($this->getAttributesUsedForSortBy() as $attribute) {
            /* @var $attribute \Magento\Eav\Model\Entity\Attribute\AbstractAttribute */
            $options[$attribute->getAttributeCode()] = $attribute->getStoreLabel();
        }

        return $options;
    }

1. To change the label do I need to extend Model/Config.php in my
   custom theme and change $options = ['position' => __('Position')]; to $options = ['position' => __('My Custom label')]; ?
2. Can this be done by extending sorter.phtml ?
3. Can we change sort by options label from admin ?