Only snaps which declare daemons will be automatically run, and the order in which the daemons from snaps start is not well defined (AFAIK it’s not deterministic though there is some design work done by the snapd team to accommodate this see Cross snap service ordering)
Note that you can control the start order of daemons within a single snap by using after and before in the snap, but this requires that you be the author of the snap. See Service ordering for more details