Adsense Ad Sizes

[alfuzzy]

I'm using Adsense Auto Ads on my website...and I currently have two adsense ads below the navbar at the top of the page that are directly above/below each other.

In the adsense code that's copied & pasted from Adsense into the ad blocks...there's no code specifying the size of the ad. The ad blocks are simply filled with what I think are 728x90 sized ads.

If I wanted to remove these two current ads...and replace them with one larger or different shape ad to fill this area (such as 970x250)...how can I modify the ad code to do this?

Here's an example of the actual Adsense ad code being used currently:

<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- ad_navbar_below -->
<ins class="adsbygoogle"
style="display:block"
data-ad-client="ca-pub-xxxxxxxxxxxxxxxx"
data-ad-slot="xxxxxxxxxx"
data-ad-format="auto"
data-full-width-responsive="true"></ins>
<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>

Thanks