How to set the form size?

oh it is visible on: https://www.cajac-nl.pcxtmp.nl/contact/

In the FORM, try increasing the size:40 value of the text and email form-tags to something higher, and also increase the columns:40 value of the textarea form-tag.

could you set an example?

Yes. Can you post a screenshot of the configuration in the FORM tab.

Thanks i already know that but where do i paste the code?

Like here:

<p>Uw naam (verplicht)
[text* your-name] </p>

or in additional settings?

You can set the maximum length of the input fields in each form-tag; however your theme’s css may override this setting.

Try this in the your-name field and see if the width increases:

<p>Uw naam (verplicht)
[text* your-name maxlength:80] </p>

I checked your website. Add this to your child theme css:

.wpcf7-form-control.wpcf7-text.wpcf7-validates-as-required, .wpcf7-form-control.wpcf7-text, .wpcf7-form-control.wpcf7-textarea.wpcf7-validates-as-required{
width: 100% !important;
}

FINALY! Your solution did work @worldsdream. but now, how to align the text to the center of the page and also how to change the buttons to something more like purple with a nice border and even a fa icon ?? ?

@barnez thanks also

Answer please?