About their participant on World cup so far Saudi Arabia has 8 appearance in this tournament and on world cup 2022 they surprising many people with beat Argentina at group phase and about their chances on 3rd round this is a bit hard for them because their opponents is Japan and Australia which these teams is strong contender for them and for the first match of 3rd round Saudi Arabia will fight against Indonesia which probably this is easy match for them
If we look at the third round of the World Cup qualifying round for the Asian zone, Saudi Arabia is in Group C. And I think the teams with the biggest chance of qualifying are Japan and Australia. They are strong teams in Asia. Saudi Arabia can qualify if they manage to get a win over one of those teams. I am not underestimating the other 3 countries but that is a realistic result based on FIFA rankings and other factors. But anything can happen in football. I am from Indonesia and I am sure that I want to see my country play in the World Cup. I see that the chance will still be there even though it is very small.
Also I am optimistic about my country like you but maybe my country still has no chance that they will qualify for FIFA world cup in football. Because according to FIFA ranking, their current position is below 150.