Clutch Question

’95 Fourtrax 300 4×4
Please pardon my inexperience here. I’m still getting to know this thing. I’m not sure if this is normal or if I need to adjust the clutch. When I take off in 1st gear, it takes a decent amount of throttle to get it rolling. Like the brake is on. It clicks through the gears fine but it seems like it takes a bit too much effort than it should to get going. I wasn’t sure if this is a normal centrifugal clutch operation or what. I’ve had all four wheels off the ground when inspecting the brakes and they all spin with little effort so I don’t think anything is dragging.
Another dumb question… how do you know a clutch is slipping?