Locating the depends entirely on the operating system of your device. Whether you are using an Android phone, an iPhone, or a tablet, your downloaded attachments are stored in specific directories managed by your device's file system. Where to Find Gmail Downloads on Android
Open your device's file manager app. This is usually named Files by Google on Pixel devices, on Samsung Galaxy phones, or simply Files on others. Tap on the Browse tab or side menu.
Select the category or navigate through Internal Storage to the Download folder.