All Apps purchased and downloaded from the App Store, including "free" Apps, are digitally signed and permanently associated with the AppleID account from which they were purchased - and are "licensed" to that AppleID. Each AppleID is effectively a different end-user.
Apps themselves cannot be transferred between devices or different AppleIDs - and neither can the ownership of licensed software be transferred to a different AppleID. This measure intentionally inhibits unauthorised sharing of purchased content between users.
You might consider using Family Sharing - allowing you to where selectively share purchased Apps, subscriptions and Apple services with your new AppleID. However, to do so, you must be able to access to the original AppleID associated with the already purchased content.
Family Sharing - Apple
Set up Family Sharing – Apple Support
Share App Store, iTunes Store and Apple Books purchases with Family Sharing – Apple Support
How to create a new Apple ID – Apple Support
https://www.imore.com/how-set-up-family-sharing-iphone-ipad
If your original AppleID credentials have been forgotten, they can be recovered here:
https://iforgot.apple.com
To recover your credentials, you’ll need access to one of the following:
- Your primary email address mailbox that corresponds with your AppleID
- Any of the secondary/recovery email addresses that should be configured for your AppleID account
- Any of the trusted telephone numbers (fixed line or Cellular/Mobile) that are associated with your AppleID
More information about recovery of your AppleID and associated Password:
If you forgot your Apple ID - Apple Support
If you forgot your Apple ID password - Apple Support