Most customers choose their boots half a size to a full size bigger than their street shoes. Tight heel fit is desirable, you should also just feel the front of the boot with your toes when putting weight on your heel/ making a heel edge turn.
Please make sure to close the lacing tight and flex your legs while trying on boots.
Simply riding your boots will give you a better than out of the box fit. The heat from your feet causes the boots to mold/ break in.