If you're asking whether the Windows Search under Windows 10 can search document content and e-mail message content the answer is yes.
I know that document content is enabled as the default. Enabling e-mail content will be dependent on the e-mail client you are using and, if memory serves, must be enabled by you once your chosen e-mail client is in place so that Windows Search knows where it's searching.
No need to apologize with regard to being used to Windows 7. We've been anticipating a wave of new Windows 10 users after Windows 7 went out of support.
Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363
Tolerance is the positive and cordial effort to understand another's beliefs, practices, and habits without necessarily sharing or accepting them.
~ Joshua Liebman