With this simple trick, the KeePassXC browser plugin can read access data from multiple databases.
KeePassXC offers the possibility to open several databases in parallel. In connection with the browser plug-in, access data can be filled out automatically on websites.
Source: Multiple databases with KeePassXC – GNU/Linux.ch (English translation by Google)
Original Source (in German): Mehrere Datenbanken mit KeePassXC – GNU/Linux.ch