If you plan to breed and use it as a grow-out tank, all of your fry should fit in there comfortably. Assuming you have an average number of 50-70 fry survive...usually a first spawn resulting in around 35-40 surviving they would fit perfectly fine in a 65 gallon tankl.
Now if you're talking about a sorority of females that are not siblings, I would say the safest number to put in a tank that size is 20-25 maximum and even that might be pushing it.
As much fun and cool this might sound to have 30 females in a tank, it would be way to risky and experimented by someone with a ton of experience. For one, I have successfully housed up to 24 females in a 55 gallon with dwarf gourami's, neon teras, mollies, platties and fancy guppies with no real aggression forming. Though I did have an advantage of having about 1/4 of them being siblings.
This isn't advised because not many are able to do this. I did push the limit a lot since I would only suggest 10-15 females in a 55 gallon and even more plants than you can imagine.
So what I'm saying is the safest number to put in your new 65 gallon would be 20-25 females with some other community fish.
Some community fish that I would suggest would be platties, mollies, neon tetras, sword tails and other live bearers.
All of those fish need to be in groups of 4 or more, preferably 6, but you can get by on 4.