Laptops must have Dell customized drivers especially chipset drivers and since there are none for windows 7 for your model, reinstall windows 10.

Even if you somehow get 7 installed, it won't update - Microsoft has blocked Windows updates for 7th generation CPU systems such as this one.  And as the second link shows, Dell doesn't support 7 on these either.

In the Windows world, with Kaby Lake and Ryzen CPUs, it's 10 or nothing.

Here's Microsoft's statement

support.microsoft.com/.../the-processor-is-not-supported-together-with-the-windows-version-that-

and here's Dell's:

www.dell.com/.../microsoft-windows-operating-system-support-for-intel-kaby-lake-processors

is there really no other ways to get the drivers other than reinstalling windows 10??

See the links above - Kaby Lake CPUs (7th generation) support Windows 10 only - nothing older.

If you must use Windows 7, return the system and re-order one with the older Skylake 6-th generation CPU - these are the last Intel CPUs that support Windows 7.