I see sentences with (he or she) like :
How to know if he or she is the best one for you?
Give a Person Power and He or She Will Show Interpersonal Sensitivity.
It's possible to use just one word instead of (he or she), something like :
Give a Person Power and He Will Show Interpersonal Sensitivity
One would typically say:
"Give a Person Power and They Will Show Interpersonal Sensitivity"
"They" being specifically gender neutral.
It's called as a 'singular they'. When the first noun is an epicene, we can put 'they' to refer to that person.
Another example can be...
If a client comes to your shop, you should treat them properly. This'll build a good relationship.
Here, the word 'client' is epicene and thus can be replaced with them. I'll also mention that I have also read he/she instead of 'singular they'. But since you are asking for a single term, it's they as suggested by books.
It is possible and, in fact, it's very common. Some websites or books will pick one singular pronoun and stick with it for the entire site while others will alternate every page or chapter to give equal representation to both genders. As an example, this site uses masculine pronouns on the pages for even weeks of pregnancy development and feminine ones on odd weeks.
If one gender is used, historically, it's always been the masculine unless the group being discussed is largely comprised of women. Generally, "he" is the "default gender". This practice is coming under recent scrutiny and the "singular they" is becoming more and more popular over the last decade, though it has been a valid option for centuries.
The singular they had emerged by the 14th century and is common in everyday spoken English, but its use has been the target of criticism since the late 19th century. Its use in formal English has increased with the trend toward gender-inclusive language.
So, which you opt to use is up to you but the above should be noted... if you want to look inclusive, use "they".
