This graph shows the outflow of energy depending of the different atmosphere composition. TLDR, There is literally no effect of doubling the amount of CO2.
The blue bell-shaped curve shows the amount of solar energy flux (at different wavelengths, x-axis) radiated to space from an earth with no atmosphere. (Most is in the infrared region 400-1000 or so.) The green line is the flux with an atmosphere with no CO2 but with all other greenhouse gases at their standard concentrations. The black line is for all greenhouse gases, CO2 included, at their standard concentrations. The red line is for twice the standard concentration of CO2 (400 to 800 ppm) but with all the other greenhouse gases unchanged.
At 400 ppm CO2 does have a greenhouse effect: Radiated energy is reduced in the 500-700 frequency range. But an increase to 800 ppm has almost no additional effect – the black and red lines are almost the same. Doubling the standard concentration of CO2 from 400 to 800 ppm has almost no additional greenhouse effect.
https://dailysceptic.org/2023/11/26/three-graphs-that-show-there-is-no-climate-crisis/