Cross compilation: special cross compiler or just gcc with option -march?

I need to compile a program for Raspberry PI 3+ on Linux machine, and code must be compliant with c++17 standard. Official toolchain is outdated and lack c++17 compilation option. Two solutions that I can see right now are:

1) gcc has an option -march, which described here: https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html

2) Installing arm-linux-gbueabi-gcc package, as proposed here: Cross-compiling for Raspberry pi with modern gcc

What is the difference between two options? Is there some other possibilities that will work?

If you want full Cross Compiler c++17 standard for your Raspberry Pi, you can try my Latest Pre-Built/Pre-Compiled Open-Sourced GCC Toolchains for Raspberry Pi along with well-documented instructions from this Github Repo:

The GCC versions available as of now are as follows:

GCC 6.3.0
GCC 7.4.0
GCC 8.2.0
GCC 8.3.0

And, the Supported Environments:

Cross-Compiler: All Linux Distros (x32/x64) are currently supported.
Native-Compiler: All Raspberry Pi version/model with Raspbian OS is supported. Other OS may/may-not work.

also the currently Supported Languages are: