Light intensity is generally measured in lux, not lumens, as lumens is what the source is producing but lux is what is observed.
Like the sun produces, I don't know exactly, but like billions or trillions or lumens, but what is important is the lux, which is how many lumens per square foot are observed on earth on a full sun day, which is about 30,000 to 100,000 lux.
It is doubtful that any basking light you are using produces 30,000 lux. Typical high powered lights are still generally only outputting around 500 to 700 lux, but maybe as high at 1,000 to 2,000 lux in close proximity like a basking light setup. This is why you need sunglasses outside, but never do inside, and typically don't even need sunglasses if you stick your head inside your lizard cage. It's still nowhere near as bright as real sunlight.
