Several reputable photography sites offer full-resolution files for public download. These samples allow you to test how the 14-bit data holds up to extreme exposure adjustments and color grading.
Their sample gallery includes dozens of high-res images, often including RAW downloads alongside full-size JPEGs to demonstrate the sensor's capabilities. gfx 50s ii raw files download
The GFX 50S II sensor is roughly than a standard 35mm full-frame sensor, allowing for larger individual pixels (5.3µm) that significantly improve the signal-to-noise ratio. Fujifilm GFX 50S II sample gallery - DPReview gfx 50s ii raw files download
Photographers like Kristoffer Trolle have shared real-world RAW files from the GFX 50S II for comparison against other systems like the X-H1. Sensor Specifications & RAW Capabilities gfx 50s ii raw files download