Presumably you had configured your Downloads folder to save downloaded files locally on your old iPad - and not to iCloud. As such, the files will only be accessible from your old iPad.
The settings path for iPadOS 17.x and earlier:
Settings > Safari > [General] Downloads > [Store Downloaded Files On] - select as required
The settings path is slightly different for PadOS 18.x:
Settings > Apps > Safari > [General] Downloads > [Store Downloaded Files On] - select as required
If you had the foresight to backup your old iPad to iCloud or iTunes, you'll be able to restore the backup to your new/replacement iPad:
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
Otherwise, if you haven't created a backup - and no longer have access to your old iPad - any locally stored files will have been lost.