I am wishing to bake smaller loafs of bread. Do I need to decrease time or temperature if dividing single loaf recipe into two smaller loafs?
When you divide your recipe into two loaves, compared to the single loaf, they will:
all other things being equal. Still, bread is relatively tolerant of varying conditions, so I would start with the original baking temperature, and monitor closely. The baking time will probably be reduced by a few minutes
It is always important to know how to test that the loaves are done, not just rely on a time. Depending on the recipe, it will be done when the internal temperature reaches something on the order of 190 to 200 F (depending on your recipe, and how enriched it is). See Fresh Baked Loaves for other tips on how to determine if a loaf is done.
If you find the loaves are baking through and you have insufficient crust development, you may try increasing the temperature slightly (in increments of about 25 F).
A lot of the answer to this depends on the shape of the loaves. If you are baking a flat bread like a foccacia then halving it won't make any difference to the baking time at all. If you are using loaf tins then halving and using smaller tins will reduce the baking time somewhat, how much depends, it's impossible to say with any certainty.
The only way to find out is to try it and see. Make sure you stay absolutely consistent with the recipe so you control for all factors.