Oh dear, the sky is falling
What a bunch of pansies..
NO, the bearings WILL BE FINE.
Get a grip people, the bearings ARE SEALED, sitting WILL NOT HURT THEM.
First things first.
You NEED to have a electric brake controller in your vehicle, no controller, no move.
Second, AIR for the tires, inflate to the side wall pressure.
Check the tires for any MAJOR cracking in the sidewalls or tread area, minor cracks can be workable provided you are not moving trailer far or at high speeds. Be prepared to remove the tires at the site if replacement is needed.
Third, you NEED a 12V battery for the trailer, this battery is critical to your trailer break away system.
Fourth, TEST the trailer brakes while parked. With 12V battery connected to the trailer you simply pull the break away pin. You will need to jack each wheel one at a time to verify the brake locks the wheel when pin is pulled and unlocks the wheel when the pin is put in the switch. If one or more does not work you will NEED to diagnose and fix BEFORE moving the trailer. Note, break away switches do go bad and might want to buy one to have on hand.
Fifth, once brakes are working plug the trailer cord into your vehicle, verify you have break controller connection.
Sixth, with trailer cord plugged into the vehicle, check and verify ALL running/marker lights work, check turn/brake lights work. Fix any lights before moving.
Seventh, make darn sure the owner HAS a legit clean title BEFORE exchanging money.. In some states, no title means the trailer is scrap..
Eighth, fix the trailer the way you want it, ignore the naysayers here, lots of negative nannys here that can't see the value in buying used..
My current 1980s trailer sat in a trailer park for 15 yrs, bearings were PERFECT, no rust and plenty of good grease.. Tires were even PASSENGER TIRES and had lots of cracks, pulled the trailer 15 miles and didn't go over 45 MPH, made the trip perfectly fine..