Pathfinder has this for Point Buy.
"After all the points are spent, apply any racial modifiers the character might have"
Starfinder doesn't, so are the final totals either 16 (-2 racial), 18, & 20 (+2 racial), or are they 18 total?
It's strictly by the order in the book, correct?
I believe it goes like this in starfinder.
Each stat starts at 10
Then you apply racial mods
Then you put your 10 points where you want them no stat can be raised over 18 at level 1.
Now apply theme bonus
If you look at the character creation in the starfinder core book it spells out specifically the order to do points and is very clear about it so it's pretty easy to get your characters attributes set. I would recommend double checking with the book as I am not 100% if the theme bonus applies before or after you start putting your points in. I am pretty sure it is after but not 100%.
Spending points is the last thing done. There is no way to start with more than 18, no matter what you do.
One interesting side effect of the way they do character creation is if you take a space goblin with +4 dex it usually just means they will wind up with more points to put to some other stat as they hit the cap pretty easy at level 1.
So not as much need/point to min max race to class.