I want this functionality on a CMS page whenever the user clicks on a particular amount it should get for checkout and should be donated. If the user entered a custom amount that amount should also go for checkout. Admin should have provision to change these 3 amounts and also have provision to enable disable amount and custom value. Anyone have any idea how to achieve this Small help will be greatly appreciated. Thanks in Advance.
You might want to take a look at this free extension for donation. They have step by step installation guide in here. If you really new with Magento 2 and installing extensions, you may see the guide on installing Magento 2 Extensions.
However, if the free extension doesn't cover your needs or requirements. You may take a look at other priced extension, here's one for an example.