@Nami *******
no one can tell you that.
It is all up to the IO you are in front of and the rules of the day.
In many cases they will warn you first, saying things like "you need the proper visa to live in Thailand"
But not always.
Things they may check:
*****
baht or equivalent cash
Accommodation proof
Ticket out of country
You take your chances, a plan B is not always a bad idea.