It is an unspoken rule that a SoP is the real deal maker or deal breaker for your visa approval.
If you are applying from Saudi, you are either a Saudi national or a resident. If you are Saudi you might have higher chances of getting the visa. However, if you are a resident, there is huge risk of rejection for your immigrant status alone, no matter how strong your case is.
Because Saudi and gulf countries in general doesn't offer permanent residency or citizenship, there is this immediate assumption that you are most likely trying to take the easy way for PR in Canada through a diploma study permit. Hence, beside documents of asset in home country, one needs to also clearly convince the officer about their intention to return home country through the SoP.
The length of the SoP doesn't really matter, it the all about the information presented in it. Ideally it should not exceed 2 pages, but even 1 page SoP could be enough if it is clearly convincing and makes sense.
All the best of luck.