How ads are created
Apple Search Ads uses the app name, subtitle, description, preview videos, and screenshots you already provided in your App Store product page to create your ad. The first sentence of your App Store product page description is the most important — this is what users can read in your ad without having to tap to read more. If you change your App Store metadata, it can take up to 24 hours to be reflected in the ad preview within your account, and up to two hours for it to be reflected in your ad on the App Store.
Tip: Review app metadata.
Since ad content relies on metadata, take the time to review your app metadata in App Store Connect before you start a campaign. Apple Search Ads doesn’t support customization of ad creative, so you can’t change the way your ad looks or upload your own ad design. However, you can use Creative Sets to create more ad variations that leverage additional App Store assets and align to your ad group keyword themes or audiences.