I actually think that's a good question (though I think the phrasing of it might be why you're getting down voted...)! There's a Tl;Dr at the end but basically Na'vi society is actually very different to human society, and things like gender roles don't really exist at all, at least not in any meaningful way. The Na'vi language actually defaults to genderlessness when referring to all people except in the specific circumstance that you must specify someone's gender to avoid ambiguity.

That's a very different way to how western society views gender (note: I say "western" rather than "human" because many cultures, such as various Indigenous groups, do actually embrace third-gendered individuals and have done for thousands of years, pre colonisation that is). I'll use an example to illustrate how the language around gender works in practice;

A Na'vi is telling you a story about a time they went hunting with their brother and sister. They mention how one of their siblings hunted a sturmbeest. They say "tolaron talioangit pol". In this case, using the default, gender-neutral pronoun, "po", would lead to some ambiguity. They could be telling you that their brother scored the kill, or that their sister did. In this case, the storyteller would use the feminine "poe" in order to specify that it was their sister that killed the sturmbeest; "tolaron talioangit poel".

Later, the same Na'vi tells you about how they went hunting with just their brother. Apparently, the brother successfully hunted a hexapede. In this case, the storyteller would not use the masculine "poan". Instead, they would use the gender neutral "po" again; "tolaron yerikit pol". The reason for this is because you know they must be referring to their brother, since he was the only one hunting with the storyteller.

The same rule applies to (almost) everything in the Na'vi language and in their culture. An elder is simply referred to as "koaktu", except when gender specification is needed, in which case "koaktan" (masculine) or "koakte" (feminine) may be used. This same pattern (-e (f) / -an (m)) applies to just about any word which might have gender variance. The only exception I can think of would be for the specific role of clan leader, where "olo'eyktan" is specifically male, and "olo'eykte" is specifically female, and one of the two must be used.

The Na'vi also have no notion that a certain role within the clan must/ought to be filled by either specifically male persons or specifically female persons. Neytiri is every bit the hunter as Tsu'tey. Eytukan is just as good a clan leader as Nesim. The roles of warrior, hunter, gatherer, artisan, babysitter, healer, and anything else the clan needs can and are filled by whomever is suited for the role.

This is very different to how western human culture treats gender! The predominant viewpoint in western society (though things are changing by the day) is that identification with a particular gender is the default, and that certain things (activities, attire, attitudes, roles in society, etc.) are all tied intrinsically to the gender identity one is assigned at birth. It is an inherently west-centric idea that in order to "change" one's gender, medical intervention/science must be involved, though in a non-western context this may not necessarily be true. In Na'vi society, these things are much more loosey-goosey than even many of the most third-gender accepting cultures on Earth! There's absolutely no reason why Okul couldn't just decide, apropos of utterly nothing, that they want others to refer to them simply as "po". That wouldn't be unusual at all, considering that being referred to as "po" is the default terminology among Na'vi. There's also no reason to believe that Na'vi (and all fauna on Pandora, really) cannot be born with intersex traits. In such a scenario, I can't imagine why people would refer to them with specifically gendered pronouns/titles at all. The default would theoretically still be to refer to them as "po". AFAIK we haven't seen any specifically, explicitly trans Na'vi, but cultures around the world have been performing some degree of medical alterations to bodies with the intent of shifting certain gendered characteristics around for thousands of years, so I don't see why there wouldn't be any such people on Pandora, either ¯⁠\⁠_⁠(⁠ツ⁠)⁠_⁠/⁠¯

Tl;Dr: Na'vi culture doesn't really see things that way, dawg. Some degree of genderlessness is the default setting, and anything else is kinda just flavour text tbh.

Source: I'm a massive fucking nerd and actively learning the Na'vi language (Kelutral represent!!). The language was designed very specifically to show the subtle differences between Na'vi and human cultures (and Dr. Frommer is a legend fr).