zdoc/layouts/shortcodes/featuredImage.html

{{ $imgSrc := false }}
{{ $params := $.Page.Params }}

{{ if $params.image }}
  {{ $imgSrc = $params.image }}
{{ else if $params.featured_image }}
  {{ $imgSrc = (print "images/" $params.featured_image) }}
{{ end }}

{{ if $imgSrc }}
  <div class="featured-image__wrapper">
    <img src="{{ $imgSrc | relURL }}" alt="{{ (.Get "alt") | default "Featured Image" }}" class="featured-image" style="width: {{ with (.Get "width") }}{{ . }}px{{ end }};height: {{ with (.Get "height") }}{{ . }}px{{ end }};">
  </div>
{{ end }}