Sforno on Genesis 19:1/ספורנו על בראשית י״ט:א׳

1ויבאו שני המלאכים סדומה בערב, even though they arrived at that city without “time” having elapsed since they departed from Avraham, (compare Berachot 4 the angel Gavriel needing two steps, and the angel Michael only one step) they remained outside the city gates, invisible, not entering and appearing to Lot until evening. The same is true of 18,22 וילכו סדומה. Avraham had concluded his dialogue with G’d already some time previously.

2ויקם לקראתם, in order to prevent them from spending the night in the street. This was customary also in cities other than Sodom when no one had offered shelter to unexpected strangers. In such instances there was always the danger that the strangers would be harmed by some of the residents of the city.

3וישתחו אפים ארצה, they clearly looked sufficiently imposing to warrant being treated deferentially.