You will have better retention of fruit aroma at lower temperatures. Generally speaking less than 10C / 50F is not practical, it will ferment but may take 6 weeks to get through the primary.
20C / 68F is convenient for many of us and the yeast like it.
30C / 97F is acceptable for yeast growth. You may finish primary in 2 days, and require extra nutrient management since the yeast is metabolizing fast. This may cause off flavors. Reds will tolerate 30C because there are background flavor notes that are not volatile. Fruity aroma will be lost at high temperature.
40C should be avoided. Some yeast strains will not tolerate 40. Off flavors are a risk. Stuck fermentation is a risk.
temperature cycles are hard on yeast and should be avoided.
NOTE if you are measuring air/ room temperature the must temperature typically is 1C/ 2F higher. Fermentation is exothermic.