AEM DAM File Uploading

If you want to restrict the Asset Upload size in Touch UI, then you need to customize the OOTB Fileupload feature as mentioned in this article:-

To configure a higher file size limit, perform the following steps in the /apps directory.
In AEM, tap Tools > General > CRXDE Lite .
In the CRXDE Lite page, in the directory window on the left, navigate to /libs/dam/gui/content/assets/jcr:content/actions/secondary/create/items/fileupload . To see the directory window, touch >> icon.
From the toolbar, tap Overlay Node . Alternatively, select Overlay Node from the context menu.
In the Overlay Node dialog, tap OK .

Refresh the browser. The overlay node /jcr_root/apps/dam/gui/content/assets/jcr:content/actions/secondary/create/items/fileupload is selected.
In the Properties tab, enter the appropriate value in bytes to increase the size limit to the desired size. For example, enter the following value to increase the size limit to 30 GB:
{sizeLimit : "32212254720"} -- Change this as per your need
From the toolbar, tap Save All .
In AEM, tap Tools > Operations > Web Console .
On the Adobe Experience Manager Web Console Bundles page, under the Name column of the table, locate and tap Adobe Granite Workflow External Process Job Handler .
In the Adobe Granite Workflow External Process Job Handler page, set the seconds for both Default Timeout and Max Timeout fields to 18000 (five hours).
Tap Save .
If you are using DM as well, then you need to change DM workflows as well:-

In AEM, tap Tools > Workflow > Models .
On the Workflow Models page, select Dynamic Media Encode Video , then tap Edit .
On the Workflow page, double-tap the Dynamic Media Video Service Process component.
In the Step Properties dialog box, under the Common tab, expand Advanced Settings .
In the Timeout field, specify a value of 18000 , then tap OK to return to the Dynamic Media Encode Video workflow page.
Near the top of the page, below the Dynamic Media Encode Video page title, tap Save .

https://docs.adobe.com/content/help/en/experience-manager-64/assets/managing/managing-video-assets.html#Configurationtouploadvideoassetsthatarelargerthan2GB