A basic question…
Wouldn’t Trump secure such things elsewhere… like a safe deposit box (public or private)?
Not classified. Classified is stored based on its level of classification. Confidential. Secret/Top Secret would be stored in a safe purpose built to store such documents. TS/SCI would be stored in a SCIF. Trump would never store classified in a personal safe or a safety deposit box, and besides, all documents he has were inventoried and recorded by the GSA and the GSA would pack and ship based upon rules and laws regarding shipping classified data.
Oh, and the president can declassify anything coming under the Executive Branch.