why you don’t want the responsive images WordPress automatically creates several sizes of each image uploaded to the media library. By including the available sizes of an image into a srcset attribute, browsers can now choose to download the most appropriate size and ignore the others—potentially saving bandwidth and speeding up page load times in the process. there is not extra work ob the user side but a positive impact on your performance.
To modify the default srcset and sizes attributes, you should use the wp_calculate_image_srcset and wp_calculate_image_sizes filters, respectively.
Overriding the srcset or sizes attributes for images not embedded in post content (e.g. post thumbnails, galleries, etc.), can be accomplished using the wp_get_attachment_image_attributes filter, similar to how other image attributes are modified.
Additionally, you can create your own custom markup patterns by using wp_get_attachment_image_srcset() directly in your templates.
at the end also your theme should call the images with the responsive functionality like:
<?php
$img_src = wp_get_attachment_image_url( $attachment_id, 'medium' );
$img_srcset = wp_get_attachment_image_srcset( $attachment_id, 'medium' );
?>
