It varies from country to country and time to time. I was lucky enough to get a pre-built model with the specs I wanted, but if not, you can choose the customize option (on either the X1E4 or the P1G4; they are for all intents and purposes the same). In the customise option, if you choose the i7-11850H processor, it should give you an option to select the iGPU only:
“The i7-11850H processor is available with Intel Integrated UHD, NVIDIA® GeForce® RTX™ 3050 Ti and 3070 graphics cards.”
P1 (Gen 4)
https://www.lenovo.com/us/en/configurator/cto/index.html?bundleId=20Y3CTO1WWUS1
X1 Extreme (Gen 4)
https://www.lenovo.com/us/en/configurator/cto/index.html?bundleId=20Y5CTO1WWUS1
The Lenovo PSREF is a useful resource when trying get more verbose information about the hardware models and configurations available.