No... Xi was a member of the CPC in his village since young, elections are taken place at different levels, from towns to municipalities and so on, until you get to the National People's Congress where there members elect a president.

For the first level, the NPC elects the head of State and the heads of the judicial organs, i.e., the President of the State, the President of the Supreme People's Court, the Procurator-General of the Supreme People's Procuratorate and the Director of the National Supervisory Commission, and, upon nomination by the President, decide on the leaders of the central administrative organs, namely, the Premier of the State Council. (Article 62 of the Constitution)

For the second level, the people’s congresses of provinces shall elect the heads of the administrative and judicial organs at the provincial level, namely, the governors of the provinces or municipalities directly under the Central Government, presidents of high people’s courts, chief procurators of the procuratorates at the provincial level and directors of the supervision committees at the same level. (Articles 8 and 44 of Local Organization Law)

For the third level, the municipal people’s congress shall elect the leaders of the municipal organs, institutions, and judicial organs, namely the mayor, presidents of intermediate people’s courts, chief procurators of the municipal procuratorate, and directors of the supervisory committee at the same level.

For the fourth level, the people's congresses of districts and counties shall elect the responsible persons of administrative organs and judicial organs at the district/county level, namely, the heads of the district/county, presidents of primary people’s courts, chief procurators of procuratorates at the district/county level, and directors of supervisory committees at the same level.

For the fifth level, the people’s congress of townships and towns shall elect the heads of the administrative organs and institution at the same levels, namely, the heads of townships/towns. There are no judicial organs in towns and townships, only agencies dispatched by judicial organs at the district/county level.

Source.

He exerts as much power as any other president, or less, he can't do whatever he wants, there are democratic processes involved to take decisions...