Is it possible to use two 240vac input 12v output smps adapter supplies in series with 400vac input
with outputs also in series to get the 24v.
The details depend on the particular converter design, but you will not
be able to put the inputs in series for 400Vac
Many AC-DC converters that are SMPS, work by rectifying line to first create a DC voltage and then a switching arrangement - the input is not just a mains transformer.
The outputs, yes but your question was for both so I believe the answer is NO.