As per the data from 2017-2018, more than 30% of the Saudi population are expats. The total number of non-Saudis in the country is estimated to be 10,736,293. Nearly a quarter of this are Syrians fleeing the war in their country. Almost 2.5 million Syrians live in Saudi Arabia and they are given free access to education and healthcare, as well as encouraged to take up jobs in the country.
Note, some related questions here (1) (2) ask if there are (than many or any) Syrian refugees in Saudi Arabia. But that hinges on the definition of refugee, in particular since Saudi Arabia doesn't recognize the notion as used in the West or international law (1951 Convention etc.) So I'm simply asking how many Syrians lived in Saudi Arabia in 2018 under whatever arrangements. Is the GMI figure of 2.48 million Syrians living in Saudi Arabia reliable/credible? (The rosy tone of the paragraph in which it is presented makes me a bit skeptical. Also note that GMI is based in Dubai, UAE, a Saudi ally for most purposes.) Also of note, one of the answers to the refugees questions simply asserts the 2.5 million number as true, based on its reproduction in some media, apparently including US News, but the article linked titles that "Saudi says [...]" so it doesn't seem an unequivocal acceptance of the figure in that US venue. Basically, can the figure be verified independently in any way, beyond something like "we trust Saudi Arabia's official number of Syrians in their country"?
For example, the GMI/Saudi data says only 1.06 million Pakistanis lived in Saudi Arabia, but France24/AFP reports (in 2019):
Pakistan has strong relations with Saudi Arabia, with more than 2.5 million of its nationals living and working in the kingdom, but it also maintains good relations with Iran and represents Tehran's consular interests in the United States.
The same number of Pakistanis in Saudi Arabia is given by RFERL/VOA. So there seem to be wild discrepancies in such expat figures between Saudi/UAE reports and others'.