Just use a Koch chart in reverse. Rather than starting with density altitude, one inputs pressure altitude and temperature. The chart gives you takeoff and rate of climb adjustments. If the chart tells you to add 100% to your sea level - ISA takeoff roll, then you know that the sea level - ISA number would be half of the roll you measured at the higher DA. Likewise with the climb rate.
Here's an online Koch chart https://www.takeofflanding.com/
If you input 3000 feet PA and 15*C, it tells you that a runway of 1000
feet would be equivalent to an ISA sea-level runway length of 680 feet.