Oh I am sorry duckman, I thought the dictionary was correct when it says “Themself is a reflexive pronoun, being a reflexive form of they. [third person singular]
used instead of ‘himself’ or ‘herself’ to refer to a person of unspecified sex:the casual observer might easily think “themself”
The form is not widely accepted in standard English. “Themself” is not listed in Merriam-Webster, the most accepted English dictionary. I’m sure you can find it and a lot of other non-words in some silly urban dictionary somewhere, but you’d still sound pretty stupid to use it.