No, that’s incorrect.
It’s “Thou are tall” or “Thou art tall”
Nominative Oblique Possessive
Thou Thee Thy/Thine*
I Me My/Mine*
He Him His
She Her Her/Hers**
You You Your/Yours**
* Used as an object (It is thine) or historically, when the following word started in the vowel (Thine eyes sparkle like diamonds, Mine ears ache)
** Used as an object (it is hers)
There’s something I call a “pill stick”, into which you put it in the barrel, jam it into the cats mouth while holding their jaw and then push the trigger. Requires a little finesse but easier than other methods.