Carl von Linné (1707-1778), botanist, professor Alexander Roslin (1718-1793)

The picture has something of this: people, portrait, leader, man, necklace, wear, elderly, veil, lid, facial expression, jacket, outerwear, wig, facial hair, jewelry, side view.
Perhaps it’s a portrait of a man with white hair wearing a brown coat and a cross in his left hand.