I want to make changes in "grid.phtml" file which is in the bellow file path at vendor side in Magento 2. path for file which need to override - " module-catalog-widget/view/frontend/templates/product/widget/content/grid.phtml".
With the help of Extension or Theme I want to override this file and want to add changes.
To override this file you can copy this grid.phtml and move it into your theme path will be :
app/design/frontend/{theme_package}/{theme}/Magento_Catalog_Wiget/templates/product/widget/content/grid.phtml
Please generate compile
bin/magento setup:di:compile
and don't forget to clear cache
bin/magento cache:clear
You can try the blow method inside your theme.
app/design/frontend/{theme_package}/{theme}/Magento_CatalogWidget/templates/product/widget/content/grid.phtml