Hi harun,
You have directly used the embedded code. You need to wrap the embedded code. You have to wrap the embed code with the class ’embed-responsive’ & ’embed-responsive-16by9′ to make responsive. So Please wrap the embedded code with the class ’embed-responsive’ and ’embed-responsive-16by9′.
<div class="embed-responsive embed-responsive-16by9">
(Paste your embedded code here)
</div>
Please paste the embedded code as mentioned above.
OR
If you are using the WordPress 5+ then you can use the Embeds Block Features of Gutenberg on the page/post editor page which will be very easy to use the embedded code with out any HTML code customization.