Welcome to cruise reviews.
Cruise ships have standard sized beds. Depending on the line and category of cabin, the usual method is the two main beds are combined into either a queen or king. Suites typically have beds which make into a king while standard cabins are queen sized, owing to the lesser floor area.
Standard cabins range from a small 119 square feet on older ships to the more usual 160-185 square feet on newer ships. Many categories are in the 200-220 sq ft range on the mainstream lines. You have to go with a suite to get anything larger than that.
Bear in mind that most people do not spend much time in their cabin.