Give the plants a good planting, in a good spot. the harsher the conditions the more dwarfed they’ll be. bamboos, in general LOVE! moisture/water (but not swampy bog, it also needs drainage), rich, healthy, fertile soil, humus/organic matter/mulch, and warmth and shelter, makes a big difference.
Once established, in about 4-7 years. best way to maintain bamboo, for beauty, health and productivity is to throughout each winter time, cut out anything that’s old and declining/dying (save and preserve for poles), and anything unattractive/stunted, really thin, or whatever else maybe overcrowding the clump. cut with japanese pruning saw above a node closest to ground level. Bamboos can be maintained in this way to keep clumps clean and open, or they can be left to be solid, full, dense clumps, which may also be desirable in certain situations.
If you want the clump to stop expanding, kick over any unwanted shoots on the outskirts of the clump.