* No rush to tighten policy amid debt defaults, global risks * China could lower 2021 budget deficit ratio to about 3% * China growth seen soaring in early 2021 BEIJING, Dec 22 (Reuters) - China’s central bank will scale back support for the economy in 2021 and cool credit growth, but fears of derailing a recovery from a pandemic-induced slump and debt defaults are likely to prevent it from tightening any time soon, policy sources said. This expands on a theme recently outlined at China’s annual Central Economic Work Conference to plan for 2021, where leaders said the country would keep its proactive fiscal policy and make monetary policy flexible and targeted.