I quickly read kbb and motortrend articles they both seem to like the EX as a value decision.
I took this from the motortrend article
2022 Kia Carnival SX Trim Pros And Cons
Stepping up to the Carnival SX trim adds even more premium touches to what's offered with the EX variant. Kia paints the 19-inch alloy wheels black and decks out the Carnival's exterior in satin and matte silver trim. SX models also receive roof rails,
power folding outside mirrors, and LED foglights.
A dual screen rear seat entertainment system is now standard. On every model below the SX trim, this feature is a $1,500 option. Critically, this model adds a 360-degree camera system, a very helpful feature when you're parking a big minivan. Kia also adds two USB charging outlets to the second row. Finally, the Carnival SX gains two 115V power inverters. Its price tag, almost $42,500, is a significant step up from the EX model, but for many, this will be the minivan to buy.
I took this from the motortrend article
2022 Kia Carnival SX Trim Pros And Cons
Stepping up to the Carnival SX trim adds even more premium touches to what's offered with the EX variant. Kia paints the 19-inch alloy wheels black and decks out the Carnival's exterior in satin and matte silver trim. SX models also receive roof rails,
power folding outside mirrors, and LED foglights.
A dual screen rear seat entertainment system is now standard. On every model below the SX trim, this feature is a $1,500 option. Critically, this model adds a 360-degree camera system, a very helpful feature when you're parking a big minivan. Kia also adds two USB charging outlets to the second row. Finally, the Carnival SX gains two 115V power inverters. Its price tag, almost $42,500, is a significant step up from the EX model, but for many, this will be the minivan to buy.