Bond funds are low-risk varieties and must be bought at one time. Fixed investment bond funds, even if held for a long time, may have certain risks, at least higher than bank bonds, and the income is not necessarily much higher than bank bonds.
It is of course necessary to guard against risks in the securities market, but we should also correctly understand risks. It is not a good investment behavior to only pursue returns and only guard against risks. Therefore, I suggest you change the fixed investment target.