Try this way:
Add JS component to your text field.
ui_component/UiForm.xml
<item name="component" xsi:type="string">Namespace_Modulename/js/form/element/text</item>
Write logic in your JS
app/code/Namespace/Modulename/view/adminhtml/web/js/form/element/text.js
define([
'jquery',
'underscore',
'uiRegistry',
'Magento_Ui/js/form/element/text',
'Magento_Ui/js/modal/modal'
], function ($,_, uiRegistry, text, modal) {
'use strict';
return select.extend({
initialize: function (){
this.addValidation();
},
addValidation: function(){
selectValue = $('input[name="labelconfig[select_field]"]').val();
if(selectValue == 'yes') {
$('input[name="labelconfig[text_field]"]').addClass("add magento validation class name");
}
},
});
});
I hope it helps!