I'm getting ready to epoxy a concrete porch floor and the concrete has 4 cracks none more than 1/16" wide and the longest is approximately 10' slab is 4" + thick can I epoxy over these or do I need a filler and if so what do you recommend, I want to use a floor leveler as there are 3 bird baths in the slab, recommendation for tis also.

Tell us more about what you are planning. Just saying epoxy doesn't tell us much, are you using epoxy to set tiles or what? Any pictures or links to your product woul be of great help.

Well If you are talking about epoxy painting the slab,
I would start by taking a small paint brush and epoxy the cracks and then see what they look like when they are dry.
Most epoxy is pretty thick, and you should be able to "fill-in" the cracks with it.
If it looks pretty good when it drys, just apply another coat and see how it looks.
If this works out for you, you should be good to go and epoxy the whole slab.