My question is if i cut off all my big fan leaves that are blocking all my little branches and leaves from getting light will that stop the stretching to a certain extent in those smaller branches?
No.
First off is it normal plant growth or stretching? If it is stretching you either lack sufficient lighting or your lighting is just to high off your plants. Either being the case nothing you could do to your plants, short of raising them, will do anything towards fixing the problem. You would have to do something or another with/to/about your lighting.
If it is just plant growth, well that is what plants do. Lower branches, as long as they receive sufficient lighting, can and will grow long and wide and tall at times. You do know how plants will increase in size greatly while in flower, so if you are in flower then for sure there should be no surprise.
As for cutting off large fan leaves off, or possibly sections of, or entire lower branches that are healthy to provide more light for buds lower down the plant is unwise. Again assuming that they are healthy leaves, they are the plant’s largest most efficient solar collectors, where most of the light rays the plant absorbs are taken in and processed into an energy form the plant uses for all of its functions. You really want to keep any such losses of healthy plant matter to a minimum. Keep in mind that energy used for growth and other functions in one area of the plant often was collected and transferred from a very different location on the plant, like say collected and transferred from the leaves you want to cut to the buds you want to receive more light so they grow larger. If you cut the healthy leaves what remaining area or areas on the plant will be able to then increase the collection of energy in that area or those areas enough to equal the loss? Where will an equal and increasing amount of energy collection be found so your buds can grow larger and larger? From the small surface they have at the time you are concerned about their size? Will that area alone be able to take in and process enough energy to cause increased growth over what would have occurred had the healthy leaves been left on the plant?
Another reason to not trim like that is whenever you cut some healthy portion of a plant from a healthy growing plant it will try to replace what was lost. Depending on what was cut and where it was cut and how it was cut and the growing conditions at that level/area of the plant regardless of hell or high water or if Pluto is in alignment with Uranus, somewhere on the plant new growth will be attempted to offset what was lost.
The standard pseudo-logic is that the new growth will be bud, that the plant will send out all this growing energy and it will be directed towards bud growth. Depending on when things are cut there can and will be some additional energy directed towards bud growth but plants always ‘want’ to maintain a certain ‘balance’ of sorts. Because of that if you cut off healthy plant matter here, the plant will likely do all it can to replace the same type of plant matter somewhere else. Energy will be used to attempt to replace leaf and or branch and the energy needed to do that, and continue to feed energy for increased bud growth, now has to do all that relying on a decreased ability to collect energy …. due to the healthy leaves and or branches having been removed in the first place. Is there a net gain if you do that?
If leaves and or branches at any level are severely damaged and or dying, as in obviously less than 50% efficient of effective and going downhill fast, go ahead and remove them.
Leave the rest on the plant.
If you are one that insists on the maximum amount of light rays directly striking buds as possible, Do not be afraid to tuck branches and or leaves or to tie branches pulling them this direction or that opening up certain areas more but still leaving them on the plant to do their job. If you feel you have to get more light to lower bud just compromise a bit and maximize as much as you can without removing healthy plant matter using other methods.
People will often times say if you trim your plants much you risk shock. Well that is true but part of what is seen as being shock causing plant growth to slow way down or stop is what I described above. The plant wants to replace what was lost. It will likely do it by adding back what was lost by spreading it all around the plant rather than just attempt to shoot out a new branch where one was cut. The growth is so spread out and so small and so slow, in part because of the loss of energy collection, that plant growth appears to have stopped or nearly stopped, when much of the time it mainly just changed in a way making it much less perceptible.
If you are concerned about lower or deep-inner buds receiving enough light maybe you might want to consider beefing up your lighting and or reflective material? Going up a bit on wattage and increasing your light penetration will always make a difference, sometimes a dramatic difference … of course not including the few people that run mega-multiple 1000-watt lighting setups. They are a different animal and this does not really apply to them. But for the rest, bump the wattage if you can and your yields will increase. Even if you only upgrade your reflective material, assuming there is something that would be an upgrade from what you now use, what seems like only a small increase in increased reflection can be what makes next to worthless popcorn into small but firm worthwhile little buds.
Cut away if you feel most comfortable and most confident doing so, but if you want or need more light to certain areas of your plants, I tend to believe there are better options much better than cutting.
