I took my ~3yo on three trips to the west coast this year. In the spring, when she was 2.75, she slept in a pack and play, just like her baby brother, and wore a pull-up on the plane, but used the airplane bathroom.
A few months later, after her third birthday, she’s fully potty trained and transitioned from crib to toddler bed, so normal underwear on the plane and a pallet on the floor to sleep.
For the time change, the biggest questions are: Does your toddler fight bedtime at home and what time are you flying? My kid loves to push her bedtime back if she can. We took evening flights in the desperate hope that we could get the 3yo and 1yo to sleep on the plane. It didn’t work on the 3yo, but she adapted quickly to the west coast time zone and was only getting up a little early. Coming east was much worse.
Your potty situation and sleeping arrangements are going to change quickly in the next few months. Sometimes these trips can actually help you push your child to try something new. I wouldn’t worry too much if it’s something you want to do.