The best fit options for a front 9" and rear 10.5" are:
225/40/20 (equal to stock diameter) + 255/35/20 (equal to stock)
245/35/20 (-1.1% vs original diameter) + 285/30/20 (-1.2% vs stock)
255/35/20 (-0.4% vs original diameter) + 295/30/20 (equal to stock)
265/30/20 (+0.8% vs original diameter) + 305/30/20 (+0.8% vs original diameter)
245/30/20 + 295/30/20 would not be a good fit because they differ by 1.1% from eachother rather than being very similar like 245/35/20 +285/30/20 is.
Pretty much you can use this table:
2019 Kia Stinger GT2 Tires
The most important thing to look at is the Diameter and how much it differs from stock, the closer to stock diameter the better, just different priorities whether you want tirewall size or width.
The second part is to look at the "wheel" column which shows what is the width of the wheel that tire is suitable for.
I am going to have exactly same fitment wheels as you and will be going with 245/35/20 + 285/30/20 most likely depending on tire availability but any of the 4 combos I named suits them.