Reducing the sensitivity of an iPhone

I think this is what you're looking for but I could be wrong, and if I am please accept my apology. But go to the settings app on your phone, or have someone do it for you if necessary. Then go to General, then Accessibility, and then VoiceOver. All the way at the end there is a setting called "Double-Tap Time-Out." You want that on the slowest setting. I've had to change this setting myself only twice: once when I first got my iPhone after I was shown how to do it by a technology tutor, and the second time for a sister of mine. But there's also a setting called 3d-Touch, and that may be what you're after. I've never dealt with 3d-touch before though and don't believe it has anything to do with VoiceOver. Hth and good luck. Also welcome to AppleVis and to the wonderful Apple ecosystem.

I think that you are looking for the 3D Touch adjustment. Depending on how heavy handed you are, this should help you with your personal situation. Go to Settings, General, Accessibility, 3D Touch. There is what is known as a "Picker Item", which allows you to changed how hard you press to activate something. To use the Picker Item, locate the area of the phone where it will say something like "medium adjustable". Once you find this, do a one finger flick up/down to change between the options. Once you have chosen what you want, there is a little test below this, where you can play with your phone to see if you like this setting. If satisfied, then just get out of settings. I have mine sent to medium and really like that setting.

I also have the Tap to Wake feature turned off because I didn't like my phone talking just because I touched it. This helps to reduce Voiceover chatter.

It should be noted that when picking up my phone, it will then speak, even if I haven't touched the screen. this is due to the fact that the iPhone is looking for Face ID info.

To change this go to Settings, General, Accessibility, Tap to Wake. Do a one finger double tap to toggle this setting.

HTH

When I first got my iPhone, the way you entered letters in an edit field was to do a one finger double tap on each letter. This is time consuming and tedious. I have Typing Style set to Touch Typing, which allows you to slide your finger across the keyboard until you frind the desired letter. Once it is found, you lift your finger and the letter is placed into the edit field. Sometimes all you need to do is roll your finger tip slightly to the right or left and the next letter can be found, as well. Mostly now I just use the Dictate feature and correct manually as necessary, if SIRI messes up something. If you use the dictate feature, just remember to speak the word for the appropriate punctuation mark to be inserted. This avoids the visual appearance of a long run-on sentence.

It should be noted that you will find the occasional spots where you will have to use the one finger double tap method to ender data, but it really depends what you are trying to do.

To change the default, go to settings, General, Accessibility, Voiceover, Typing Style. Open this and change the setting to Touch Typing.

HTH