As per the information, the update is currently rolling out in Ukraine and will expand to other regions pretty soon. The Android 11 update for Galaxy A70 carries firmware version A705FNXXU5DUC6 and requires a big chunk of data, 1902MB to be precise.  The One UI 3.1 along with Android 11 brings tons of new features which include Object eraser tool, Private share, Chat bubbles, One-time permission, Built-in screen recorder, Samsung free, and Eye comfort shield.  The update should hit your Galaxy A70 with a pop-up notification. Alternatively, users can manually check for the latest builds by navigating to Settings » Software update.

Samsung Galaxy A70 getting Android 11  One UI 3 1  update - 41