Does the lightening in the last two rak'ahs include standing, bowing, and prostrating, or is it restricted to standing only?

It is from the Sunnah for the Imam to lengthen the first two rak'ahs and shorten the latter two. This shortening includes the bowing (rukū') and prostration (sujūd). Sa'd ibn Abi Waqqas, may Allah be pleased with him, said: "I used to lead them in prayer with the prayer of the Messenger of Allah, peace and blessings be upon him, his 'Ashi prayers (Dhuhr and Asr), I would not deviate from it. I would prolong the first two and shorten the latter two." This is because when the Prophet, peace and blessings be upon him, prolonged his standing (qiyām), he would prolong his bowing and prostration, and when he shortened his standing, he would shorten them. The Prophet, peace and blessings be upon him, said: "Give every surah its share of bowing and prostration."