I could find no evidence that the 400 Series cameras have HDR (High Dynamic Range) or WDR (Wide Dynamic Range). The only mention of HDR is in terms of an Intel article containing an analysis of the rationale for choosing parts for the RealSense camera range. Features like HDR are apparently supported in cameras with more expensive CMOS sensors.
To quote the article: "if long range and high quality are paramount and the product is less sensitive price, it will be possible to use higher performance CMOS sensors (higher dynamic range, more sensitivity and higher quality) as well as better and larger optics so that the input images are of high quality. In the other extreme where cost and size are critical, it is possible to use small baseline, cheap consumer-grade CMOS sensors, and plastic optics".
The 400 Series cameras do though have a component called the Vision Processor D4 that enables the camera to perform well in outdoor sunlight.
This message was posted on behalf of Intel Corporation
Getting much better quality with the RGB camera with a backlit scene would be a challenge. However, there are RGB controls like Gain and Exposure that you can modify to slightly improve RGB capture quality.