show/hide custom fields on click

This could be done with a UIkit toggle or Bootstrap collapse (see https://getuikit.com/docs/toggle or https://getbootstrap.com/docs/3.3/javascript/#collapse).

If you have difficulties let me know and I'll try to assist you

Hello, thank you jor the answer.
As I am displaying an "articles by category blog" the collapse method works fine with a "details" link for the first article but if the same link appears on the other articles, it opens the custom field layouts in the same first article.
I want the same behavior for each article displayed,of course.
I send images
Thank you for your help, best regards

You need a unique ID in the layout.

So where you have collapseExample you would need to incorporate an item id in some way. This isn't currently possible in EasyLayouts - I'll take a look as see what is possible.

Ok - not so hard

Edit the file administrator/components/com_easylayouts/output/common/custom_field.php and add these new lines

		foreach (array("subform_wrappertop", "subform_wrappertop") as $wrapperfield)

		{

			$field[$wrapperfield] = str_replace("{ID}", isset($item->id) ? $item->id : "", $field[$wrapperfield]);

		}

at line 34 just after

		$field["subform_wrappertop"] = str_replace('{FIELDNAME}', $heading, $field["subform_wrappertop"]);

		$field["subform_wrapperbottom"] = str_replace('{FIELDNAME}', $heading, $field["subform_wrapperbottom"]);

Then change your wrapper HTML use use

collapseExample{ID}

I'll include this change in the next release of EasyLayouts