The important thing that Trump needed to do was destroy enthusiasm. Because this primarily hits Dem votes. Trump doesn't need to preach policy, so long as his voters are scared by the boogeyman - and chuds always are. Biden needed to lay down promise and policy. The only voters that can be hooked in at this point are potential Dem voters who are looking for an excuse to go to the voting booth.
There was none.
Mostly Trump took advantage of Biden's memory and speach issues by constantly barraging and confusing Biden's points and policies. Look at the post debate polls. It worked.
Donny 1, Joe 0
The important thing that Trump needed to do was destroy enthusiasm.
Per the exit polls during the debate, Biden continued to lead Trump 48/41. The undecides stated they were less likely to vote. That's of dubious benefit to the guy who isn't the frontrunner.
I'd say this would be worse for Biden if the Undecided pool had grown, rather than people doubling down on their prior biases. But hey, I guess time will tell.