In the large majority of homes, yes, a staircase can be fitted to a loft conversion. A proper fixed staircase is a building regulations requirement for any habitable loft room, so ladders and retractable stairs are not an option once the space is a bedroom or office.
The two things that decide how the stair works are where it lands on the floor below and how much headroom there is at the top. Building regulations set minimums for the pitch, the rise and going of each step, and the headroom over the flight, usually 2 metres, reduced to 1.9 metres at the centre and 1.8 metres at the edge where space is tight.
In older or smaller homes where space is limited, the answer is often a bespoke staircase: a flight made to measure to fit the available run, sometimes with winders (angled steps) to turn a corner, or a space-saver stair with alternating treads where regulations allow it for a single room.
The best position for a loft stair is usually directly above the existing staircase, so the two flights stack and you lose the least floor space. We work this out at survey stage and build the stair to suit, so it is safe, compliant and takes as little room as possible.