if traveling by air from 74 degree weather to 25 degree weather how does one dress?

will it get cold on the plane

Wear jeans and a long sleeve shirt, and carry on a jacket for when you get off the plane. It should remain comfortable in the plane the entire flight, so you could alternatively pack a jacket in your luggage that would be easily accessible when you get off the plane and collect your luggage.

jeans and a sweatshirt and carry a jacket

No it does not get cold on the plane. You could wear a winter jacket after you get off the plane and outside obviously. But when you get dressed you could wear pants and a long sleeve shirt. Bring a hat and gloves with you and a sweatshirt to wear underneath your jacket just in case if a jacket isn't enough. I usually just wear pants and a jacket when it's 25 degrees out but that's just me and I wear the clothes that I would wear when it's 74 degrees out if I was traveling like you. And again that's just me. Most people would wear what I suggested you wear.

Depends on your tolerance of temperatures. Wear jeans & a comfortable shirt getting on the plane. Pack a heavy jacket, sweatshirt & thermal underwear in your carry on or where it can be grabbed easily in your checked in luggage, so towards the end of your flight or after landing you can go to the bathroom & put the thermals on & layer up to be comfortable.

It never gets cold on the plane regardless of how cold it is outside. I strongly suggest you DO NOT carry along a jacket or any other extra clothing (just what you wear at room temperature). It will only be a hindrance at security and you have to stow it somewhere. Unless you're planning to walk from your destination airport to your place of accommodation, you don't even need to unpack a jacket. 25 degrees isn't that cold. I have travelled without a jacket to destinations where it was 20 below zero. I just nipped into my friend's car quickly, and quickly from the car to my hotel. 25 is very mild.