Putin is going to take Southern/Eastern Ukraine up to the Dnieper river. The only question is whether he’s going to try to take Odessa and cut off Ukraine entirely from the Black Sea.
I haven't seen any military analyst listing that as a serious possibility. 100k Russian troops could conquer that area, but would be insufficient to control it later. That area is heavily populated with a Ukrainian majority. More credible is creating a Russian land bridge to Crimea which would also solve their water issues.