I want to remove my front wheel on a folding bike with hydraulic brakes for traveling will brakes get out of adjustment or do I need to put something between pads?

There is a plastic wedge you put in.

Thanks just what I needed

I lost my wedges. I now just take a piece of an old inner tube and stretch it till it fits in the gap, then let it expand to hold itself in and keep the pistons in place.

My road bike inner tube was too thin, but an old tube from my kids mountain bikes was thicker and works well. But you can use most anything you can shove in there.

If you have Shimano disc brake calipers, just go to a local bike shop and ask politely to buy a couple of caliper spacers, which are about $2 each, and they would most likely give them to you for free because they have so many left over after setting up disc brakes.

so i can use a 20 oz. framing hammer's claws?
or a bic pen ink tube? not the body of the pen, but the ink tube inside.... sans ink, of course...
a buddy used a trojan still in the package once...
sorry... couldn't resist....

or a folded up business card works well. use a couple zip ties or twist ties to hold it in place during shipping.

When I transport my disc brake bike, I just don't touch the lever.

same. Never had a trouble in 20 years, and I transport by removing front wheel and racking inside SUV.

"Toilet shims" aka wedges, work perfectly for disc calipers when the wheel is removed. They're just the right size. Available in any hardware store for less than $5 for a half dozen.
Multi-Purpose E-Z Wedge Toilet Shims (6-Pack) - Plumbing Parts by Danco

If you can shove it in there you can use it.

You'll have to use your own common sense on whether it will damage the pads, caliper body or anything else.

If you are going to be passing the bike on to me without the wheels installed, I might suggest you use $100.00 bills in sufficient quantity to make a thick enough layer to wedge in there!! <grin>

Getting back to suggestions for the OP:

Some bike shops might just have some laying around and give them away for free or just charge a pittance for them. Certain little things like this tend to accumulate where bikes are assembled regularly. I got my tool for plugging and unplugging Di2 wire free simply by asking at one of the LBS's here. He picked up half a dozen of them from nooks and crannies nearby in his shop area before finally handing me one. Not sure what he was looking for but I saw no damage on the one he gave me, and free is free so I wouldn't care if it was scratched or dinged.