In the colder weather,my daughters 2019 Subaru wrx only runs right if I disconnected and the reconnect the battery, only for a short time.?
It's a brand new car. Take it back to the dealer.
Use your damn warranty and quit messing with the new car before you end up voiding the warranty.
It's a brand new vehicle, it'll be under warranty. Resist the temptation to tamper, and take it back to your dealer.