Build me a smart contract in Etherium With Private Sale (similar to ICO)

We are starting a project and we wanted someone to create a smart contract for us on eth network. It's better to just fork a project and modify it as per our needs. We wanted to implement a ladderized tax. The more you sell, the higher your tax will be. This tax will be distributed to the holders. We also want to have a private sale. We will whitelist some investors. Their wallets are the only ones eligible to buy during the private sale. They can send eth to the smart contract and they can receive their token right away. After the private sale, we can have presale which can be done through dxsale. We have already a roadmap till 2022 Q2 and we have lots of updates/upgrades to do as well as development of new tokens. We wanted to work with someone midterm and not only for this project. I will give more info privately.