Decrypt single files without restore entire installation

i deleted one file 3 months ago, so i can’t find that on my recycle bin or in a deleted files on nextcloud.
i have a backup (tar.gz) with php files + mysql backup.
can i restore quicky single xls file without restore entire installation (20gb)?

thank you in advance

my installation is simple lamp with php 7.3
nextcloud is 18.0.6
no app installed, only encryption enabled…

thank you

fow now, i upload entire 20gb installation (with long time…) and recover my single file.

i hope , for future, can i decrypt single file in a simple way…

thank you anyway