Hi Nana___nananana
welcome to the Apple (user-to-user) Community :-)
Re: Set up talk to text on Iphone : The thing is I need talk to text and don't know a thing about Iphones.
Am no expert in this area, yet your question surely deserves some response.
Others with more expertise may yet join the discussion, and the articles below may be a starting point.
Underneath, have included information on a new feature that communicates using spoken words that you type.
RTT (real-time text) allows you to send text messages with a recipient during a phone call.
RTT can also be used with a TTY (teletypewriter) device.
This feature is available for plans from carriers in the United States and Canada only.
Standard voice call rates apply for both Software and Hardware RTT/TTY calls.
Depending on your carrier, you might see RTT, TTY, or RTT/TTY.
If this RTT feature interests you: Apple support have an article online that may be helpful to you:
Answer or make RTT or TTY calls from your iPhone - Apple Support
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On iPhone you can now use Live Speech:
With Live Speech on iPhone, you can type and have your words spoken in person, on Phone and FaceTime calls, and in assistive communication apps using any of dozens of voices, including your Personal Voice. (Available in select languages.) See how to: Type to speak using Live Speech on iPhone - Apple Support
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More help / support / contact options etc. if needed:
How to contact Apple for accessibility support - Apple Support
or
Apple's Accessibility Support Website
(NB: You can "Get Support" from the link at the bottom of their website:)
Accessibility Support - Official Apple Support
All the best :-)