It's not a simple thing IMO, where you can just sit on a bike and because everything is within reach it fits!
I have spent a lot of time tweaking things, stem lengths, saddle position and so on. Then I had a bike made for me by Roberts and it was almost perfect from day one. The only change I made to their set up was to lower the saddle nose by an almost imperceptible amount.
Earlier I had a bike made for me by a shop who will be nameless* and it was a shambles, so not all bike shops are your friend. The last bike I bought, for utility, was from
Evans, York this year. They were helpful, let me go out for a good test ride, twice.
* a long time ago now.