This is just a method i used to make me able to include bits/stdc++.h in visual studio 2019. for those had minGW installed on PC :
C:\MinGW\mingw32\lib\gcc\mingw32\4.8.1\include\c++\mingw32\bits
copy this 'bits' folder and then go to this address
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.24.28314\include
and paste your folder. go to your visual studio project and type bits you will see the auto-complete for the library and then choose bits\stdc++.h
for those don't have minGW: you should write your own header file and include all libraries in it then go to
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.24.28314\include
i have added the bits folder to oneDrive you can fetch the file here-> https://1drv.ms/u/s!ApWwSDDAnudpgnxstyu5i_11-5mq?e=P75vtv
make new folder name it "bits" and name the header file stdc++.h then paste it in "bits" folder.
Hope this helps!
Happy coding