The M1 powered MacBook is one of the thin & light that meets your requirement & has great performance with good iGPU. Get that if you are fine with its limitations, like soldered RAM & storage, to name 2 major ones.
For Windows, stick with Ryzen 5000 powered CPUs. The i7 11th gen U CPUs don't perform near Ryzen 5000 U CPUs in multicore workloads, not sure how CPU intensive AutoCAD is though.
IMO this is the best thin & light laptop for you:
ASUS Zenbook13{2021} (R7-5700U/16GB RAM/1 TB NVMe SSD/Win10+McAfee/Ms Office H&S 2019/13.3-inch FHD IPS OLED/Integrated Radeon Graphic/FP Reader/1.4 kg/Grey/1 Yr.)UM325UA-KG701TS: Amazon.in: Computers & Accessories
Review:
Asus ZenBook 13 OLED UM325 review (UM325UA 2021 model, Ryzen 5000 U)
The OLED panel is glossy, not anti-reflective, so beware. It runs the CPU at 15W & even at 15W it outperforms i7 10750H, which is a 45W performance-oriented CPU. Its iGPU is ok, should be fine IMO.