How can I set an image’s alt text from an ACF field?
I tried this https://nimb.ws/VjawAH, but no luck.
At a guess, you would need to run a hook on post publish/update.
The hook could then use the get_field value and update the alt.
You would need to get the image attachment ID and then you can use:
$image_alt = get_field('image_alt');
update_post_meta($attachment_id, '_wp_attachment_image_alt', $image_alt);