Re: "I have an IPhone 16 Pro with IOS 18.5. I turned on Apple Intelligence and attempted to turn on type to Siri but there is only a toggle for talk to Siri. I also looked in accessibility for Siri and have no type to Siri toggle there."
Apple support's online article (link below) for iOS 18 may be helpful:
See how to: Use Apple Intelligence with Siri on iPhone - Apple Support
Eg says:
"Type to Siri
When you don’t want to speak out loud, you can type to Siri—
for example, when you’re in a quiet place like a meeting or a library.
To type to Siri, double-tap the bottom of the screen, then enter your request.
To turn off Type to Siri, go to Settings > Apple Intelligence & Siri,
tap Talk & Type to Siri, then turn off Type to Siri."
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If needed: See what to do: If Siri isn't working on your iPhone - Apple Support