AusBonsai

I would appreciate your advice.
I was thinking to defoliate my Japanese maple, the internodes are quite long and the leaves are quite big.
Although I am aware that this variety of Japanese maple has big leaves.
I leave in Sydney

Thanks

You can defoliate if you want however defoliation does not always result in smaller leaves or shorter internodes.
Proper pruning is much more effective I think.
I notice you have wired a small branch low to the right. It is at the same level as the main branch growing left. WHY? Leaving 2 branches will thicken the trunk at that point. You should always try to remove shoots completely where there is more than 2 (branch and main stem). Only leave a V fork at any spot on your tree. I think there will be other places on this tree where there are such multi shoot forks. Thinning all of them will reduce the tree's vigour and will eventually reduce internode length.
I can also see a very strong nearly vertical shoot a little higher un the trunk. What is that there for? Get rid of strong vertical shoots unless you have a purpose for them. They will also thicken the trunk in the wrong places if allowed to grow.

Japanese maple initial spring growth is usually very strong with large leaves and long internodes. When you get that do not be frightened to cut any strong shoots off right near the base. Lots of new shoots will grow and many will have shorter internodes.

Maybe you do not know that Japanese maples are quite hard to keep looking good in the long term unless you are really good with your pruning. I recommend Trident maple to learn on. They are far more forgiving and much easier to recover when you realise you have missed some desirable aspects of your pruning.

Thank you for your comments and suggestions.
I got this tree just few days ago, all the wiring were already done.
I thought to start with a defoliation and at the same time to shape the tree.
I will think about your suggestions. Thanks