You can visit whatever resorts at Disney World you'd like. That's not a problem. The problem arises if you are planning to drive and park there. Then it's tougher. They would likely not let you park at YC without a dining reservation. Boardwalk is a little different, since folks do sometimes drive there for evening entertainment and dining. BW has a pretty large self-park area (it's a pretty good walk from the parking lot to the resort), but they also offer valet parking for a fee (probably $30-$35, not sure what the cost is since Covid).
So if you're planning to visit resorts, it's better to plan on using Disney transportation (or Uber/Lyft/cab) to get there. For most resorts, parking is only for guests of the resort, or those dining at the resort.