What level?
These are all "classified":
Classified, secret, top secret, top secret/SCI, FOUO.
Each of these have differing impacts on national security based on their level. As do the consequences for having them in ones possession. And some increase in level based on what other documents are nearby.
I know Trump held TS and TS/SCI materials in his possession, which are considered the most egregious and prosecutable offense. What about Biden's docs, were they similar classifications?
*Source is I worked in the security field, and held a TS/SCI clearance at one point.