I think maybe Trump could have an opening statement, where he could voice his own perspectives, but just pray they are not lies! Lies under oath pertaining to an enquiry by Congress, is a prosecuted crime..... So he has to be really careful....
But then after his opening statement, as with all depositions, he will be asked questions, and he will have to answer them, truthfully.... or plead the 5th amendment. Direct fact finding questions, direct answers.... There is not much leeway.
Trump's lawyers advised him not to testify, all but one, who thinks maybe it would be ok, is what was reported...
He won't do it is my bet....well, because he never has testified under oath.... all the times he claimed he would.... Hide and watch, this will be no different!