Select “TBS SmartAudio” in the peripherals column and use the VTX table linked in the article.

You are probably talking about the attenuator for the measurements above the 1W (1000mW). Actually this device has some margin above the 1W and allows to measure slightly more than one watt. if going above that, it shows the warning message on the screen, saying you need to use attenuator.
Also the RF power output measurements are just for the reference. They are not absolute right values for EVERY VTX. Each of the VTX can have its own different results. Results also are dependent on the thermal environment, MMCX to SMA pigtail quality and etc. I always use the pigtail supplied with the VTX in my tests.

Thanks for the info. Made a VTX Table file and linked it in the article.

I assume you already configured the VTX table in Video Transmission page. If not you can download it from here and import file into Betaflight: https://github.com/betaflight/betaflight/wiki/VTX-Tables
You can manually adjust not correct\missing values from the printed VTX manual.

My problem was the power level values on the bottom of the page.
After you set “Number of power levels” to 4, there are two lines with input fields: “Value” and “Label”.
The solution: Instead of setting “Value” fields to dbm values, just write this: 0 1 2 3
And so the labels are: 25, 200, 600, 1000
Save it and now you can test it by selecting power from Betaflight Video Transmitter\Select Mode

Might be the some case with the VTX tables, introduced in BF 4.1. Don’t know the solution. Share it if you’ll find the way.