The presidential poll released by Fox News on October 30, 2020 had Biden 52% Trump 44%. The actual results were Biden 51.3% Trump 46.8%. So the Fox poll could be giving Biden 1% more support and Trump 3% less support. If the June Fox poll is Biden 50% Trump 48%, I think the actual result would be Biden 48% Trump 51% if there is no third party candidate.
That assumes they have made no changes to their methods. That’s not a good assumption.