2x4’s or 2x6’s for shed floor base?
I’m still new to learning how to build things on my own so please bear with me. I have built a 12ft by 22ft run in shelter for my horses but so far that’s it other than furniture kits etc (I included a picture of my run in so you can understand). I now need a feed shed. I need many things but my next on the list is their feed shed. I bought a 8ft by 12ft metal storage shed (included a picture of that as well). It’s ugly lol but it was on sale for super cheap.
I’m trying to figure out the best way to frame out a floor and build it. I watched a lot of videos and people were just using 2x4’s to frame it out then putting plywood on top. So my current plan was to use deck blocks on all four corners, in the middle on each side, and one every other board down the middle. Frame out the floor with gc pressure treated 2x4’s, strong tie the joints, and attach 3/4” thick gc pressure treated plywood. I was planning to do two 12ft long boards for the long side, two 8ft long boards for the short sides, then 8ft long boards 2ft OC through the middle. I do understand I have to make sure the floor base is level and understand how to do so. I recently saw a post saying something about 2x4’s have to be a minimum of 12” OC then the comments saying even with that spacing 2x4’s is not enough and that you should use 2x6’s. I’ve now gone down a rabbit hole and getting more lost the further I go. Can someone please help me understand which is the better route to go?