While "blocks" are native to AutoCAD, Revit uses "Families." For BIM level 2 or 3 projects, you need a parametric Revit family for PPR pipe fittings.
Standard metal pipe fittings have a different insertion depth. If you use a steel fitting block, your bill of materials (BOM) will be wrong. A PPR pipe fittings CAD block always accounts for 2-3cm of pipe insertion loss per joint. ppr pipe fittings cad block