No. Article 4 of Qatar's Labour Law makes it very clear that the rights set out in the law represent the minimum entitlements for all workers. Any contractual terms or conditions that fall below these minimums are considered null and void — even if you agreed to them before the law came into effect, or signed a contract accepting lesser terms.
This means that if your employment contract offers fewer days of annual leave, lower end-of-service gratuity, or worse conditions than those prescribed by the law, those clauses cannot be legally enforced against you. The law automatically steps in to protect you.
As a practical matter, if you suspect your contract contains terms that undercut your legal rights, you should consult the Ministry of Labour in Qatar or seek independent legal advice. You cannot legally 'waive' your minimum rights under this law, so do not feel pressured to accept below-standard terms simply because they appear in a signed contract.
This is general legal information, not legal advice. For advice on your specific situation, consult a lawyer licensed in Qatar.