How can I install Windows 7 on new pc with modern hardware

There are two main reasons why you can't install Windows 7 on new PC with modern hardware.

Newer computers often have newer hardware components, such as newer graphics cards, network cards, sound cards, etc. The official driver library for Windows 7 may not have drivers for these newer hardware. For example, some new computers with 12th generation or higher Intel Core processors may not have drivers for their motherboard chipsets and integrated graphics cards under Windows 7, which may result in unrecognized or improperly functioning hardware during installation.

And many new computers default to UEFI, while Windows 7 was originally designed for traditional BIOS boot mode. While it is possible to get Windows 7 to install in UEFI mode by some means, this can run into compatibility issues. For example, when installing Windows 7 in UEFI mode, there may be boot partition format incompatibility, as UEFI usually requires the GPT partition format, while Windows 7 traditional installation is more adapted to the MBR partition.