Easy way to fit lock on bedroom door?

[Puddleduck2013]

Is there a straightforward way to fit a bedroom door lock - lockable from both sides?
I’m not much of a DIYer but would give it a go if not too complicated?

Easiest is to change to an identical handle/knob that locks

would it need to be key operated from outside?

Bump

No, you basically want the bathroom version of whatever handle or knob is there now.