LittleForBigCotton Romper Onesie Pajamas Bodysuit – Classic Japanese School Girls Onesie Skirt Set Pink

I am 5”9 and a uk size 8 and i am not entirely sure what sizing i should get as i am worried it will not fit, can someone help me with this?

Does it come in discreet packaging?

What are the sizes, one size is very large but on chart by the item is is a smaller size

Can a male be able to wear this without it feeling quite tight anywhere?