Is there a way to change the starting population for the player race in a new game? I'm trying to do a conventional start with a mostly-accurate population for Earth (i. e. several billion rather than 500 million).
I always did this previously, before I have up on Earth and did random systems. Easiest is to just change it at game creation. You can easily edit the number now, but previously I had to set the Industry and Wealth % much lower (basically at same ratio than default 500-1000m), otherwise you had really powerful industry and everything and could strip systems of resources superfast, industry is still here but I see no wealth so not sure about that. I would advise to play like this for now, I do the same, the patches will break our games anyway most likely so we will have to start again.
Edit:
If you like to go for realism I also like to add more name themes for commanders and edit their values. Like US, English, French, German, Italian, Russian, Spanish, Turkish, Arabic, Persian, Indian, Indonesian, Chinese and Portugese. I try to add those which have sufficiently high pop and political clout to be used as commanders, with their % chance roughly equal to pop size to importance ratio. It is a small cosmetic thing but over time it leads to nice varied name list.