can we create custom user filter for a read only grid without using record source data in appian

Why not. Populate your grid using query entity and pass your user filters to your query. 

ok i will try it,but now i have created with using local variable  in grid data with nested if condition for two dropdown filter,

i have two filter (department and isActive ) so in this way i can show 2 filter in same grid 

a!localVariables(
local!department: a!refreshVariable(
value: rule!EAD_QE_fetchAllDepartmentDetail(id: null),
refreshAlways: cons!EAD_BOOLEAN_VALUES_ARRAY[1],

),
local!selected,
local!activeDep,
local!datas:rule!EAD_QE_fetchAllDepartmentDetail(department: local!selected),
local!active:rule!EAD_QE_fetchAllDepartmentDetail(isActive: local!activeDep),

),

 a!gridField(

data: if(a!isNullOrEmpty(local!selected),if(a!isNullOrEmpty(local!activeDep),local!department,local!active),local!datas),

),

is it correct way @Harshit Bumb?