I have to strongly disagree with the vast majority of the replies you're getting.
But you also need to take some decisions for them in order to keep them safe and healthy. ...Most of the things OP mentioned have nothing to do with safety or health. Hair length no difference at all to a boy's health or safety, otherwise girls would be getting clipper cuts too. The idea that boys should have their hair cut short despite their own preferences to grow it longer, seems very regressive.
I want him to have the choice over his own body such as haircuts, shower or bath, what's clothes etc. Okay, let's look at each of these examples:
Haircuts: literally make no difference to their wellbeing so let the child decide
Shower or bath: Parents' responsibility to make sure basic hygiene is maintained, but whenever it's practical, why not let the child decide whether they prefer a bath or a shower?
Which clothes: Parents' responsibility to make sure child is dressed appropriately for the weather conditions but in terms of wearing the monster top or the fire engine top, why not let the child decide?
Parenting is not all about exerting control over your children. You control the things that matter to their wellbeing and you let them have a say over the little things. You set boundaries (it's cold today, we can't go outside unless you've got a jumper on) but you let them have freedom within these boundaries (which jumper do you want to wear?). Of course, some kids aren't bothered which jumper they wear, and they're happy to just be provided with whatever you give them. In that case, there's no need to force them to make decisions constantly, but if they seem frustrated about having little control over their life, it can actually be a nice simple mood-booster to give them choice over little things.
Also if you don't have a bit of control at five how do you expect him to listen to you at fifteen. It's actually the opposite: if you exert control over insignificant things like haircuts age five, how do you expect him to respect your guidance about more important things age fifteen? It's pointlessly authoritarian, making it more likely that they'll see you as an adversary, more likely to invite power struggles, and less likely that they'll respect your decisions about other things that actually do matter.