Is “After Cao Cao pacified Jingzhou, did he appoint Wen Ping, a former general of Liu Biao, as the Grand Administrator of Jiangxia?” true?

Indeed it is so. The official history, Records of the Three Kingdoms, in the 'Annals of Emperor Wu' (武帝纪), records that after Cao Cao accepted Liu Cong's surrender, 'he then discussed the merits of those who had submitted to him from Jingzhou, and enfeoffed fifteen men as marquises, appointing Liu Biao's general Wen Ping as Grand Administrator of Jiangxia, and allowing him to command his original troops.' In Chapter 41 of Romance of the Three Kingdoms, Cao Cao praises Wen Ping as 'a true loyal minister,' and then 'appointed him Grand Administrator of Jiangxia and granted him the title of Marquis of Guannei.' The novel's arrangement of appointing Wen Ping as Grand Administrator of Jiangxia is completely consistent with the official history.