What is the ruling on praying to increase one’s height? And is it permissible to change the jawline through exercise?
Question

Is praying to increase ones height considered as the transgressions of dua?
And does making jawlines(which is very common in youngsters these days)considered as changing the creation of Allah if it's not done by surgery but by excercises?
Praise be to Allah.Firstly:
When a person has passed the growth stage, meaning that it is usually not possible to increase in height, then praying to increase one’s height is a transgression of du`a (supplication).
What we have found out regarding the age at which a man stops growing is:
A growth spurt begins in males at the onset of puberty – i.e., between 10 and 13 years of age – and usually they continue to grow until the age of 16, but growth may continue after that time until the early 20s.
In response to a question about when a man stops growing, there are other factors which may affect that, such as:

Genes inherited from the father and mother. This is one of the most significant factors that may play an important role in growth, as it has an impact of 80% on how much a person will grow.
Levels of hormones in the blood, such as growth hormones, thyroid hormones and reproductive hormones, and whether there is any problem with the levels of these hormones.
Diet and the extent to which essential nutrients are found in it.
Activity levels during childhood.
The mother’s nutrition during pregnancy.
The individual’s state of health and whether there are any chronic illnesses that could affect growth.
The presence of genetic discrepancies in some hereditary conditions, such as Down syndrome and Marfan syndrome.

End quote from at-Tibb website.
If specialist doctors state that a man has reached an age after which it is usually impossible for him to grow any further, then praying for an increase in height is a transgression of du`a, because of what it involves of poor etiquette towards Allah by asking Him to do something different to what He has decreed for His creation.
Abu Dawud (96), Ibn Majah (3864) and Ahmad (16847) narrated that ‘Abdullah ibn Mughaffal heard his son say: O Allah, I ask You for the white palace on the right-hand side of Paradise, if I enter it. He said: O my son, ask Allah for Paradise and seek refuge with Him from Hell, for I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “There will be people among this ummah who will transgress in purification and supplication.”
This hadith was classed as sahih by al-Albani in Sahih Abi Dawud.
Al-Qarafi (may Allah have mercy on him) said: The second category of that which is prohibited but does not reach the level of disbelief is when a supplicant asks Allah, may He be exalted, for things that are ordinarily impossible unless one is a prophet, for the usual practice of the prophets (blessings and peace be upon them) is to do extraordinary feats or miracles, so that is permissible for them, as they called for a table to be sent down from heaven, and for the she-camel to be brought forth from the solid rock…
As for what is prohibited, there are several examples:
1. Asking Allah, may He be exalted, to make you have no need to breathe air, so as to be protected from suffocation, when usually that is impossible.
2. Asking Allah, may He be exalted, for freedom from sickness all your life, so that you can benefit from your strength, senses and physical faculties throughout your life, when usually that is impossible.
3. Asking Allah, may He be exalted, for a child without having intercourse, or for fruits without planting and tending trees, when usually that is impossible, so asking for that constitutes poor etiquette towards Allah, may He be exalted…
Rather every wise person must understand the way in which Allah, may He be exalted, manages and controls His creation, and he should recognise the connection between cause and effect in this world and the hereafter, whilst acknowledging the possibility that by His power, effects may come about through other causes or without any cause at all, for in fact Allah, may He be exalted, has ordained His dominion according to a particular system and has set it up with all the natural laws that He has ordained and decreed, and He is not to be questioned about what He does [al-Anbiya’ 21:23]. So if the supplicant asks Allah, may He be exalted, to change His dominion and go against the system that He has ordained, and to do things in a manner other than that in which He usually does them in His dominion, then he is showing poor etiquette towards Allah, may He be glorified and exalted; in fact that would be poor etiquette towards the lowest of rulers and even governors."(Al-Furuq  4/368).
Secondly:
What is meant by the jawline is the outline of the jaw and its shape from the side.
There is nothing wrong with defining the jawline by means of exercises, but not by means of surgery or injecting fillers.
These exercises – according to what we found out – have other benefits besides defining the jawline. Please see this link.
As for injections and surgery, they are not permissible unless they are done to correct a defect.
Please see the answer to question no. 47694 .
And Allah knows best.