Kind of, by engaging in any kind of thrust you change the velocity. Simplistically think of two objects on a grid: A and B with the top being North, bottom South etc.
A is travelling north at a speed of 1 square per second. B is travelling north at a speed of 10 squares per second. Both of them apply thrust so that they are moving west at 1 square per second. For A this means that for every square it travels north it travels 1 west (creating a 45 degree angle if this grid were a graph). For B it travels 1 square west for every 10 north.
However you only have to nudge a tiny bit to be very off course over long distances. Let's posit B (a RKV now) travelling at 150,000,000 mps (~0.5c) and at some point it thrusts to one side (let's say port) so that it is travelling 1 metre to port for every 150,000,000 metres it travels forward. Over the course of a light hour (two hours of travel) it is now 3.6 km off course to port. Over a light year it would be 62,000 km off course!
And that is only supposing it sticks to the measly thrust that generates 1mps to port!