Normally it’s not a problem, however it’s probably best to draw out the sealant before shipping. I’ve received bikes with sealant just fine, but one time it leaked all over the inside of the box because the tire deflated. It was a mess to clean up. Just a thought.
If you deflate to 1/2 the normal pressure, there should not be a problem.
Most tubeless tyres fit tighter on the rim than normal clinchers, and wouldn’t just come off because there is no air in them. If yours come off easily, it’s probably best to take the sealant out first.