Yes, in D&D 5e, a cleric can Bless 5e water to create holy water. This is accomplished through a special ritual, not directly via the Bless 5e spell. The ritual takes 1 hour to perform, uses 25 gp worth of powdered silver, and requires the caster to expend a 1st-level spell slot. The details are found in the equipment section of the Player's Handbook under 'Holy Water.'