Just got a IS 350 fsport last week and i am still struggling to find a comfortable position. Any tips im around 5'10 190lbs if that helps.

 

I find I sit myself lower in our IS350 FS than I do in our ES300h both are 2023 models. So maybe try a lower seat cushion position?

The IS has for me the most comfortable seats I’ve had and I’m over 50 and have had a lot of decent to nice cars. But the older I get the more sensitive I am to the seat cushions.

5’11” 175lbs. Speaking of old, I used to be six feet tall lol.

 

It could also be you're just new to the car and have to get used to it?