There is a mitzva to stand up and show respect for a Talmid Chochom. What about letting him ahead of you when you are online in the grocery? Rav Moshe Shternbuch (1:532) says that this is as good as it gets with regard to with regard to showing respect.
He compares this to the Halacha in Shulchan Aruch (YD 243:4) that paskens that you must let a talmid chochom sell his merchandise before you, if you carry the same items. This way the tamid chochom can get back to his learning. Although there is a question of whether anybody has the status of a talmid chochom nowadays, regarding this halacha says Rav Shternbuch, if he learns all the time you should allow him to checkout first. Rav Shternbuch is amazed that we don’t act this way nowadays.
He adds a caveat that this only applies to an occasional meeting with the talmid chochom. However if the talmid chochom takes advantage of his priority on line, then it is worthwhile not to let him go ahead since it appears like he is using the crown of Torah for his own personal use, and trouncing upon the heads of a Holy Nation.