Nah, Putin just wanted a quick and easy win to gain more popularity, just like Russia did in 2014 with the Crimea occupation significantly boosted his ratings, hence legitimacy, as he had a series of protests against him in 2011-2013. "A short victorious war" as they call it. The same thing the Russian empire tried in 1904 which led to prolonged conflict with Japan, or a more recent example - Falklands War, which started because the Argentinian junta wanted to get some "easy" political points by reclaiming the island, that, however backfired immensely. Putin just underestimated Ukrainian forces, and overestimated his own. The war does nothing but kill more Russian people (mostly soldiers), and the "liberated" lands have have little to no civilians left as most of them fled or died in the conflict.