Yes, absolutely. Saudi Arabia's Anti-Cyber Crime Law applies to anyone in the Kingdom, including expats, and social media posts are fully within its scope. Under Article 6, publishing content that violates public order, religious values, public morals, or personal privacy online can result in imprisonment of up to five years and a fine of up to three million riyals.
This means posts that mock religion, share indecent content, defame individuals, or are deemed politically sensitive can all trigger criminal liability. The law does not distinguish between a Saudi national and a foreign resident — if you are physically in the Kingdom and posting online, you are subject to these rules.
Practical advice for expats: avoid sharing content that could be considered offensive to Islam or Saudi culture, do not repost or share material that originates from others if it falls into these categories (as Article 9 also punishes those who assist or collaborate in committing a cybercrime), and be especially careful with private messaging apps, which are also covered. When in doubt, don't post.
This is general legal information, not legal advice. For advice on your specific situation, consult a lawyer licensed in Saudi Arabia.