I get it from MSI Afterburner tool - A great tool to see Average fps, (low, and high fps),power draw, frequencies, usage (e.g. of all cores and GPU), temperatures and some more. Youtubers use it a lot when they do comparisons between CPUs, GPUs in order to show results.
In addition - especially for RTX 4090 - with the tool you can save around 20% of power draw of the rtx 4090 with performance loss of less than 5% to none.
I can recommend to try it out - maybe watch some youtubes like Undervolting GPU and