Yes we do. We know precisely when Trump left office.
Do you understand that as POTUS he had the right to possess any classified document?
'Had' is the operative word. Neither Trump nor Pence still hold an official qualifying office. Their right to possess classified documents expire when the new administration was sworn in. It could be argued that presently, of the three, Biden is the only person with the authority to classify, declassify or possess these classified documents.
You may want to take the time to read the following information published by the National archives.
https://www.archives.gov/isoo/policy-documents/cnsi-eo.html#fourThe President Executive Order 13526
Classified National Security Information
December 29, 2009
Below are some relevant sections of the President Executive Order 13526
sec. 1.3. Classification Authority.
(a) The authority to classify information
originally may be exercised only by:
(1)
the President and the Vice President;(c) Delegation of original classification authority.
(2) ‘‘Top Secret’’ original classification authority may be delegated only by
the President, the Vice President, or an agency head or official designated pursuant to paragraph (a)(2) of this section.(3) ‘‘Secret’’ or ‘‘Confidential’’ original classification authority may be delegated
only by the President, the Vice President, an agency head or official designated pursuant to paragraph (a)(2) of this section, or the senior agency official designated under section 5.4(d) of this order, provided that official has been delegated ‘‘Top Secret’’ original classification authority by the agency head.
Sec. 3.1. Authority for Declassification. (a) Information shall be declassified as soon as it no longer meets the standards for classification under this order.
(b) Information shall be declassified or downgraded by:
(1) the official who authorized the original classification, if that official is still serving in the same position and has original classification authority;
(Note: neither Trump, Biden or Pence were/are serving in the same position as they did when the documents were originally classified. Of the three men, Biden is currently the only person with the authority to classify or declassify government documents.)