convert 240Vac into variable voltage of 24 Vdc to 30Vdc?

trying to make a power supply that will allow me to vary the output voltage of 24Vdc to 30Vdc
need help from all here
regard
thanks

The current to be supplied is important.

Regulation, ripple and duty might matter but your application might not be that complicated.

An outline of one approach: a transformer to drop the mains voltage down, a rectifier and filter capacitors, a variable voltage regulator such as an LM317 or LM338.

There are other ways to do this too.