Can I use Philips SCF358/00 Bottle warmer to thaw and heat frozen Breastmilk storage bag?

If can fit in, yes. But most probably you’ll have to run under running water for awhile to “loosen” the pack if you can’t fit in. Alternatively you can bring down the pack the night (fridge) or a few hours (room temp) before to let it thaw then pour to bottle to heat and serve directly.