Change topbar menu width

The modifications you may be looking for can be done in your child theme:

if you copy of the templates/header.php file into your child theme, you can edit the markup on line 7:
from:

<div class="col-md-6 col-sm-6 kad-topbar-left">

to:

<div class="col-md-12 col-sm-12 kad-topbar-left">

and then you’d probably want to remove the search bar if you aren’t using it, which is around line 47:

<div class="col-md-6 col-sm-6 kad-topbar-right">
          <div id="topbar-search" class="topbar-widget">
            <?php if(kadence_display_topbar_widget()) { if(is_active_sidebar('topbarright')) { dynamic_sidebar('topbarright'); }
              } else { if(kadence_display_top_search()) {get_search_form();}
          } ?>
        </div>

Also, for the second row, there is a little php looking for which type of layout you selected. If you are going with your current one, then:
this:

<?php if(isset($virtue['logo_layout'])) {
  if($virtue['logo_layout'] == 'logocenter') {$logocclass = 'col-md-12'; $menulclass = 'col-md-12';}
  else if($virtue['logo_layout'] == 'logohalf') {$logocclass = 'col-md-6'; $menulclass = 'col-md-6';}
  else {$logocclass = 'col-md-4'; $menulclass = 'col-md-8';}
} else {$logocclass = 'col-md-4'; $menulclass = 'col-md-8'; }?>

could become:

<?php if(isset($virtue['logo_layout'])) {
  if($virtue['logo_layout'] == 'logocenter') {$logocclass = 'col-md-12'; $menulclass = 'col-md-12';}
  else if($virtue['logo_layout'] == 'logohalf') {$logocclass = 'col-md-6'; $menulclass = 'col-md-6';}
  else {$logocclass = 'col-md-0'; $menulclass = 'col-md-12';}
} else {$logocclass = 'col-md-0'; $menulclass = 'col-md-12'; }?>

but you may have y=to add a col-md-0 to your css:

.col-md-0 {
width: 0;
}

This isn’t perfect, but it will get you where you want I believe.

I will suggest just adding this in your theme options > advanced settings:

.kad-header-right, .kad-header-left, .kad-topbar-right, .kad-topbar-left {
    width: 100%;
}

Kadence Themes

Late response but thank you both, tried the second option first and that works perfectly. Stacy, thanks for the great explaination tho!