Whether an agreement of sale cum gpa holder can execute a sale deed in his favour i.e., self,

No, the GPA holder cannot directly sell the property. According to the Supreme Court of India, a power of attorney is not a document of transfer concerning any right, title, or ownership of immovable property. As a result, the Indian Supreme Court issued an order barring municipal organizations from changing or registering properties based on such documents. In contrast, the Supreme Court upheld the legality of lawful GPA transactions. 

GPA is a term for general power of attorney. You can provide a GPA execution to his spouse, son, daughter, brother, sister, or any other family to handle the property as a registered property owner (the person whose name is on the title to the property in government records, usually the Registrar's Office). The GPA document (or deed) must be registered with the Registrar's Office or another authorized institution to become a legitimate legal document.

Can a GPA holder execute a sale deed?

No, the GPA holder cannot execute a sale deed without the owner's consent. The court stated that nothing prevents concerned parties from obtaining registered deeds of conveyance to confirm their ownership. Section 53 A of the 1882 Transfer of Property Act can be used to obtain particular performance or to keep possession. As a result of the Supreme Court's decision, many Indian states have made it illegal to register property sold through a GPA.

Furthermore, the Supreme Court's landmark decision has already aided in limiting the unrestrained flow of black money in India's real estate sector, where property titles are frequently corrupted.

By the Sale Agreement, Cum General Power of Attorney, ownership rights were not transferred. Suraj Lamp Industries Private Ltd v. State of Haryana was a case decided by the Supreme Court.

Agent cannot become principle. If the agent is intrested then need to execute another sale deed  document where the original owner will be the seller and GPA as normal buyer where his previous status of a gpa holder will not be mentionef