those types of cracks have varying reasons as to why they get cracks,
could be due to shipping(dropping), expanding and shrinking of the wood
its ok if the damage is only to the clear coat (to a guitar that you like), what i use is this
(
https://www.fixitsale.com/?MID=1288185), if you dont have this you can use CA glue or clearcoat and then buff it afterwards after leveling that finish ( i wouldnt recommend that with a brand new guitar)
its best to find a guitar that has both body and neck that is already stable (which is hard to determine), a neck that will expand and contract alot will give you more problems in the long run