I am trying to retrieve data from an old custom programming to a new WordPress site, but I encountered a problem that I cannot retrieve the old id number. I need that to keep the site’s archive, the number of posts is more than 10,000.

I have tried the wp all import plugin, but it does not give the option to enter the id, but there is the option to add lines of code I don’t know if it will help.

Is there a solution? Or a hint?