In-feed ads are responsive which means they automatically adjust their size and ad settings for the device they're being viewed on. However, if your feed styles are different on mobile versus desktop, we recommend that you create separate In-feed ads, one for each screen size.
You can place multiple In-feed ads in your feed, but we recommend you have at least three content blocks between each ad. If you want to place more than one ad in your feed you can either create multiple In-feed ads or place the same In-feed ad code multiple times in your feed.
You can choose to also show display ads inside your In-feed ad units. Showing both types of ads can help to increase your revenue. You can turn this option off in the "Global options" of your In-feed ad settings.