The default Khmer font on Telegram for computers is small. To solve this problem, you need to change the default font of Microsoft Windows by updating the registry.
*Method 1*
Download this font !KhmerOSBattambang.ttf or !KhmerOSSiemreap.ttf install it then restart your Computer or Telegram.
*Method 2*
Step 1: Press Win+R to open Run and then type Regedit.
Step 3: Then change MS Shell Dlg2 to Khmer Font that you want to put and click Ok to finish.
Step 4: Restart Telegram and you will see Khmer font bigger than before.