I’ve read your post a few times and I’m still not sure what your actual question is. You may want to rephrase your post to better convey what you’re looking for (or maybe it’s just me!)

I’m not sure I really understand the question. ‘this’ and ‘that’ are both used to tlsk about something when it’s obvious from context what you’re referring to.

Situation - in a bakery “i want that” (pointing at the cake on the shelf) “I want this too” (pointing at the bread by the counter) Next customer “i want the same”

Situation - you’re on a date in fancy restaurant, you’re date has just finished explaining she wants to have lots of children “I want that” (the children she’s been discussing) “but I want this too” (gesturing around at the adult single life you’re enjoying " " I want this too" she reassures you

I don’t think there’s much variation between the main English dialects / varities. This and that are key grammatical words.

British English has a lot more variance than Yankspeak.

We’re more likely to use “help V+ing” than “help INF”. An average larger vocabulary, atop different usages. Even with US dominated media eroding our dialects faster than ever there’s still a lot of difference out there.

I will need a more specific question to give more response. Are you a non-native English speaker living in the UK?

Can you give some more context for your question? It sounds like you might be replying to someone who just expressed a desire for something that you also want, but the specifics of the situation might make one reply feel more natural than another.

But based on nothing else, I’d say “I want that.” Or “I want that, too.” sounds natural to me, an East Coast American in the NYC area.

Also, looking at your posts, your English seems pretty natural, I wouldn’t guess you’re a non-native speaker reading what you write online. I can see some over-formality that I know to look for something deviant, but it’s not immediately apparent.

(UK) All three are technically correct, but 1 and 3 are the most commonly used. 1 is casual and the most frequently said (mainly because it has fewer syllables and we humans are lazy).

Edit: Thinking about this more. Phrase 1 is what you would normally use when you desire something that is not shared with others, for example:

“I found this old slice of bread behind the sofa…”

“I want that!”

Or “This week’s jackpot is 1 billion pounds!”

“I WANT THAT!”

Phrase 2 or 3 are normally used when you are expressing a common desire.

“I wish this skyscraper would just fall on top of me so I don’t have to go to work tomorrow” “I want the same”

“I wish Uncle would stop drinking.” “I want this too, but he is very thirsty.”

I’m not sure if I would qualify as the demographic you seem to anticipate. I am an ethnic Pacific Islander with a Kiwi accent currently in Vermont whose family comes from a place with what may be referred to as an English pidgin, and I’m told a combination of hypergraphia, selective mutism, and overall neurodivergence affects the linguistic experience as well. I would probably hold the title for the person with the worst communicative experiences here, yet at the same time might be able to bestow some help upon you, if that’s alright with you.