From mid-August, Microsoft have announced that you will be able to create a poll in an email, without having to manually install the poll add-in option.
For Windows there are 2 ways you can do this:
For Outlook on the web:
What if I already have the poll add-in installed?
If you use Mac or Outlook for the web and have downloaded the Quick Poll add-in, you will need to uninstall it at https://outlook.office365.com/ecp/ in order to use the pre-installed Poll add-in.
When you preemptively uninstalls the old add-in, the new Poll add-in will be automatically installed.