An example of plotting a typical vector-valued (aka parametric) function:

ParametricPlot3D[ { 2*Sin[t], 3*Cos[t], t }, {t,0,4*Pi}, BoxRatios -> 3,3,1} ]

If all uses of the parameter are inside the same function or expression, you can replace that expression by another variable to “reparameterize.”

ParametricPlot3D[ { 2*Cos[t], 3*Cos[t], Cos[t] }, {t,0,4*Pi} ]

ParametricPlot3D[ { 2*s, 3*s, s }, {s,0,4*Pi} ]

Conical helix :

ParametricPlot3D[ {t*Sin[t], t*Cos[t], t }, {t,0,50*Pi} ]