Hi

Thanks for contacting us. Could you please give me your site URL and also screenshot of your issue?

-Regards.

https://ibb.co/PhbtQwg on all site, mobile menu lookblike this, hiw create full width?

Give me one site URL so that I can check.

https://somaticfields.com/

Use this custom CSS

.offcanvas-menu{
  width: 400px !important;
}

Path towards custom CSS: Extensions>Templates>Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.