Traditionally agencies and consulting firms grow vertically through a pyramid structure adding junior layers and mid level professionals who can be paid at a lower level and then billed back at higher rates to the clients as they scale once the rainmaker fills the pipeline. Another option is to grow horizontally and compensate people for bringing in work thereby gaining leverage through a network effect of casting a wider net. Both ways can work it is a matter of strengths and preferences.
It is a good question if the growth of the company is well structured defined and firm or it is dynamic to mirror the growth.
The growth path is generally on the lines of the focus the leadership has in this growth period. If the leadership is focused on results the evolution of a growing tech consulting company is casual, dynamic and result oriented. The staff will be performing multiple roles and the org structure would be lean
However if the leadership is focused on performance and process oriented, then there is likely to be hierarchy ( whether it is projectised or matrixed or could be hybrid) .
Whatever is the focus however this would be the right time to bring formalization in the processes and results.