What sensor do I use to measure the intensity of direct sunlight? I'm trying to measure how bright the day is on a particular day to see how it affects plant growth. The brightest sun can be 120,000 lux. It possible to measure such a large brightness? What sensor do I use?

The best options I've found is the BH1750FVI since its sheet says, "[i]t is possible to detect min. 0.11 lx, max. 100000 lx"

However, it still doesn't go high enough.

Note: I live "only" 3,494 km (2171 miles) from the equator, and it can get fairly bright here.
You can use a photo resistor. It is also known as an  LDR (Light dependent resistors) and here is a great tutorial to do just that. You can also find a conversion from the 8-bit analog value to lumens if you wish. Here is a tutorial:
https://www.instructables.com/id/Measuring-Light-Using-Light-Sensor/
You can also use a LUX which is the advanced version of a LDR. Here is a tutorial:
https://www.instructables.com/id/How-to-Measure-LUX-With-Arduino/