Short answer is no, there is no real simple way of hardening the water long term.
Short term hardening the water is simple enough by adding baking soda for example but this is only for very short term for fishless cycling a tank for example if the ph is too low.
But long term will require complex chemistry and knowledge of water hardness.
Not for novices intro he hobby imho, in fact won’t recommend this for most keeper to be entirely honest.
Much easier to find fish species to suit your water than it is to alter water to suit your fish species.