To get up the water tower platform to find evidence of Scrambles in The Hundred Hands of Chaos in South Park: The Fractured But Whole enter investigation mode and use Snap N Pops to break all fractures in the wood:
Highlight the lava and select the blower icon:
Go to the highlighted area and follow the button prompts. Stand next to the piece of wood and enter the time controls and reverse time:
Then use Snap N Pops to only blow up the left fracture in the wood:
Now use the pieces of wood to climb up to the water tower platform.