Hi saranchi96,
We think you have directly used the embedded code. Please wrap the embedded code with the class ’embed-responsive’ and ’embed-responsive-16by9′.
Example
<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.
Thanks