It’s a custom work so there is no documentation.

I hope you are well today and thank you for your question.

There are no plugins and WordPress options to achieve this as it is a custom requirement.

You can achieve this by developing a custom code.

If you are not a developer, you can consider hiring a developer to develop it. You can hire a developer from any freelance site or WordPress agency.

You can also consider hiring me to develop it for you using the form https://ivorysearch.com/custom-work/

Best regards,
Ivory Search Support

Thank you very much!

I could confirm the issue and it will be resolved in the future version of the plugin.

You can resolve this by adding the below CSS code in the Custom CSS option of Ivory Search plugin settings on the path Admin Area -> Ivory Search -> Settings -> Settings

form.is-form-style.is-form-style-3 input.is-search-input {
    border-right: 1px solid #ccc!important;
}