The verse refers to 'for some have entertained Angels unawares.' This is linked in my Scofield Standard Reference Bible to the episode when the two Angels came to Abram's camp and he entertained them as traditional hospitality required, and Sarah laughed in private at their prediction (of her giving birth) unaware that they were Angels. Gideon also was visited by an Angel who appeared as 'manish'.
An Angel rolled back the stone of Jesus' tomb, an Angel released the door and chains that bound Apostles. The reference you cited doesn't mean that in every case Angels are unidentifiable.
The Angel in the desert led the Hebrews as a cloud during the day and a column of fire at night. A heavenly host of Angels appeared to the shepherds heralding the birth of the Lord. These appearances were not misundertood as something other than Angels. If you happen to find references to Angels in the Bible that do not appear at roughly human size, THAT is what I'm seeking to explore. Thanks for your patience ...
I haven't seen anything like that...