I don’t see how you can compare confidence between say, TM and NS, why should they be similar, they are two completely different characters.
In any case, NS may be not particularly confident inside herself, which makes sense of the suit of armour that she wears : eye watering bright suits, the type you often see at a wedding, very high heels and pancake style make up.
The most comfortable with herself Leader is Angela Merkel,
She is confident but exudes some warmth, and wears trousers and jacket and flat or flat-ish shoes.
NS seems confident ( whether she is or not) but also cocky.
T May not being confident with how she looks or comes over in general has no bearing on how confident she is as a politician.Tbh could she really have carried on as she has with everything that has been thrown at her, if she wasn’t?