Craft + imager data-srcset macro.

srcSet.twig

{% macro srcSet(image) %}

	{# Lazyload + WebP enable iamge tag. #}

	{# Create image sizes in JPG format #}
	{% set jpg = [
		{ width: 1080 , format: 'jpg' },
		{ width: 900 ,  format: 'jpg'},
		{ width: 720 ,  format: 'jpg'},
		{ width: 480 ,  format: 'jpg'  }
	] %}
	{% set srcsetJpg = craft.imager.transformImage(image, jpg) %}

	{# Check for WebP support and create images if available. #}
	{% if craft.imager.serverSupportsWebp() %}
		{% set webp = [
		{ width: 1080 , format: 'webp' },
		{ width: 900 , format: 'webp'},
		{ width: 720 , format: 'webp' },
		{ width: 480 , format: 'webp'  }
	] %} 
	{% set srcsetWebp = craft.imager.transformImage(image, webp) %}
	{% endif %}

	<picture>

	{# Create a <source> element with the set of webP images.  This will only be used in browsers that like webp. #}
	{% if webp is defined  %}
		<source sizes="100vw" srcset="{{ craft.imager.srcset(srcsetWebp) }}" type="image/webp">
	{% endif %}

	{# Create the standard JPG using the smallest availabe element as SRC, with the srcset of JPGs for all browsers.  #}

	<img class="lazyload" src="{{ srcsetJpg[3].url }}" sizes="100vw" srcset="{{ craft.imager.srcset(srcsetJpg) }}" alt="{{ image.title }}" height="auto" width="100%">

	</picture>

{% endmacro%}