for index, row in df_override.iterrows():
    if(not str(row["name"]).isdigit()):
        df.loc[df["name"] == row["name"], row["Field"]] = row["New Value"]
    else:
        df.loc[df["id"] == row["name"], row["Field"]] = row["New Value"]

fields = df_override["Field"].values
names = df_override["name"].values
values = df_override["New Value"].values

for field, name, value in zip(fields, names, values):
    if not str(name).isdigit():
        df[field] = np.where(df["name"]  == name, df[field], value)
    else:
        df[field] = np.where(df["id"]  == name, df[field], value)

fields = df_override["Field"].values
names = df_override["name"].values
values = df_override["New Value"].values

if not str(name).isdigit():
    df[fields] = np.where(df["name"]  == names, df[fields], values)
else:
    df[fields] = np.where(df["id"]  == names, df[fields], values)

df_override
"name"  "Field"  "New Value"
apple    color     red
100     is_number  True

df
"name" "id" "color"  "is_number"
apple   300   blue      False
apple   200   yellow    False
banana  100   green     False

df (after processing)
"name" "id" "color"  "is_number"
apple  300    red       False
apple  200    red       False
banana 100    green     True