No, in most cases you don’t need a job offer.
But, you will need one if you:
- are eligible for either the Federal Skilled Worker Program or the Federal Skilled Trades Program, and
- do not have enough money to support yourself and your family in Canada.
Even if you don’t need one, you may want to try and find a valid job offer. It will give you a much higher point score, and so a better chance of being invited to apply.