It wasn't quite clear to me what sort of defence he might be preparing unless it's "Yeah, you got me, but you didn't do it in a way I think you should have so it's not fair".
I expect the approach will be to argue that the prosecution has not met the high burden of proof beyond a reasonable doubt. The prosecution will probably show the known facts about the murders, the known facts about Kohberger, and how those link up.
The defense will probably present things from a perspective of the investigation that led to Kohberger being identified as a suspect. The will argue that guesses and assumptions and confirmation bias led investigators down that path. A car that is probably associated with the murders, a guess that his car is the same car, a police report that appears to be associated with that car, a phone number that appears on that report, an assumption that Kohberger was driving that car that night, genealogical DNA evidence that casts a wide net where Kohberger was included but was not an exclusive match.
The defense will argue that there were certain guess made in each step, which when added together constitute reasonable doubt. That investigations cherry picked certain evidence to match their pre-conceived assumptions that made it look like there were remarkable coincidences when those things were actually quite ordinary.
That isn't a super strong argument in itself, but it sets up the defenses big argument that prosecution has presented absolutely no evidence that Kohberger was at the scene of the murder. They have a sheath that he had touched at some point. A car that is similar to his. His phone (but not him or even his car) was tracked in the general area at the time (but not to the location of the murder). A witness who can't positively identify Kohberger
and only matches a vague subjective description. They have no motive. And that is it. Nothing that shows that it was actually him in that house. It is reasonable that it could have been anybody with a similar car who happened to have a sheath that he had touched at some point. Reasonable doubt.
The defense might even suggest that it is possible that somebody stole his car with his phone and knife sheath in it and committed the murders and returned the car. They don't have to prove that is what happened. The prosecution has the burden to prove that is not a possibility, otherwise there is reasonable doubt.
It is then up to the jury to decide whether the evidence is conclusive enough for conviction to send a person to prison for life, or whether the lack of evidence that he was actually there and other possible scenarios constitute reasonable doubt.