It is available if you have an Office 365 subscription and the latest version of Office. You can get the latest version and buy a subscription on Microsoft's official web page
.Home license costs 140 UAH/month for 1 PC, and 180 UAH/month for 5 PCs. Makes sense to buy it if you often need to make presentations.
In PowerPoint Online, Morph (Transition) is only available when you work with files that were saved on SharePoint Online.
If you are using Mac and cannot find Morph, follow this instruction