[napy8gen]

For your old ads you can do these changes.

for example normal ads:

<ins class="adsbygoogle"
style="display:inline-block;width:728px;height:90px"
data-ad-client="ca-pub-2517459423514138"
data-ad-slot="2028335009"></ins>

make responsive by these changes.

<ins class="adsbygoogle"
style="display:block;"
data-ad-client="ca-pub-2517459423514138"
data-ad-slot="2028335009"
data-ad-format="auto"
></ins>

New ads you can just pick up the responsive ads from your adsense account when creating new ads.

[napy8gen]

Or you can set a css class for different size like this:
https://support.google.com/adsense/answer/6307124?hl=en