<blockquote>CobaltBlue73 said: - I think there is a system that lets you learn abilities but can this system grant you equipment items instead</blockquote>
There are different ways to learn abilities. One of them, research trees, can be used to also get equipment, items, quests, status values, etc.
Otherwise you could e.g. use crafting recipes to get the equipment, or have your tomes add them via their schematics.
<blockquote>CobaltBlue73 said: - Can I change the number of available equipment slots based on increasing a status value?</blockquote>
Not automatically.
Equipment slots can be added or removed in different ways, e.g. passive abilities, status effects or using schematics (Change Equipment Slot node). So, you could e.g. set up a Change Schematic on your status value that impacts the available slots, do checks in the schematic and add/remove slots as needed.