Yes, of course.
Let me take a module named: What makes us different? on this page as sample: https://ja-impact.demo.joomlart.com/index.php/about
It's JA ACM Features : style-2 module so we will edit 2 files:
root/templates/ja_impact/acm/features/tmpl/style-2.php
root/templates/ja_impact/acm/features/tmpl/style-2.xml
In the style-2.xml file, I will add a new field so you can input the alt text for the image:
<!-- image -->
<field name="sub-feature-img" class="not-required" type="media" default="" label="FEATURES_IMAGE_LABEL" description="FEATURES_IMAGE_DESC" />
<field name="img-alt" class="not-required" type="text" default="" label="FEATURES_IMAGE_ALT" description="FEATURES_IMAGE_ALT_DESC" />
and modify the style-2.php to load this alt text field:
<div class="item-media <?php echo $widthMedia; ?>">
<img src="<?php echo $helper->get('sub-feature-img', $i) ?>" alt="<?php echo $helper->get('img-alt', $i) ?>">
</div>
I attach 2 files here so you can see the update: