Hi Vimalraj Jayamani,
Thank you for reaching Microsoft Community.
The Surface Laptop 4 (Surface Laptop 4: Ultra-Thin Touchscreen Laptop - Microsoft Surface) can either be the 13.5" or 15" version. Measurements for these sizes respectively are as follows:
Surface Laptop 4 13.5”:
308 mm × 223 mm × 14.5 mm (12.1” × 8.8” × 0.57”)
Surface Laptop 4 15”:
339.5 mm × 244 mm × 14.7 mm (13.4” × 9.6” × 0.58”)
To know which configuration you have, you may enter the serial number here: Check Warranty Page - ROBO SelfServe Portal (surface.com). See this page for reference in getting the serial number: Find the serial number on your Microsoft or Surface device - Microsoft Support.
Regarding with the issue, may I know what display issue are you experiencing on your Surface Laptop 4? Screen size should not be needed also in raising a ticket with our live support. You could just provide the serial number of the device. May I know where you were asked for the screen size? Was it by the support representative?
Kind regards,
Marrion