Princess Sophie-Charlotte became Princess Eitel Friedrich on 27 February 1906 so this card is from before that date.
From eBay; sepia tone removed by gogm.
Princess Sophie Charlotte wears a dress with a vee or scoop neckline framed by a lace bertha in this post card.
Keywords: Princess Eitel-Fritz, Princess, Oldenburg family, Hohenzollern family, German, bouffant coiffure, vee neckline, bertha, lace, quarter length sleeves, necklace, brooch, bracelets, boa, fur