ClearCollect(colTest,
    AddColumns
    (
        ‘Assessment Details‘,
        "zzTextField",
        assessmentquestionid.‘Question Text‘,
        "GUID1"
        assessmentquestionid.‘Assessment Question‘, /*Get GUID field Name of Assessment Question lookup field*/
        "GUID2",
        ""
    )
);
ClearCollect(coltest3,colTest);
ClearCollect(coltest4,‘Assessment Question‘);
ForAll(
    coltest4,
    ForAll(
        coltest3,
        If(
            ‘Assessment Question‘ = GUID1,
            Patch(
                colTest,
                LookUp(
                    colTest,
                    ‘Assessment Details‘ = coltest3[@‘Assessment Details‘]
                ),
                {
                    GUID2: LookUp(
                        ‘Assessment Question‘,
                        ‘Assessment Question‘ = coltest4[@‘Assessment Question‘],
                        ‘Assessment Section‘.‘Assessment Section‘ /* LookUpfied.GUID */
                    )
                }
            )
        )
    )
)L

Lookup Field in collect - powerapps