Here in the printer’s manuscript, Oliver Cowdery initially wrote “& persued him until he had came to the plains of Heshlon”. Later, with somewhat heavier ink flow, Oliver corrected the reading to “& did persue him until he came to the plains of Heshlon”; that is, he added the do auxiliary to the verb pursue and changed the perfect had came to the simple past-tense came. Oliver probably made the change when he proofed 𝓟 against 𝓞. In this instance, 𝓞 is extant for this part of the verse and reads as corrected in 𝓟.
See under Ether 10:8 for other cases here in the book of Ether where Oliver Cowdery initially omitted the do auxiliary. For Oliver’s tendency to add the perfect auxiliary had in subordinate clauses, see under Alma 31:8–9.
Summary: Maintain in Ether 13:28 the reading in 𝓞: “and did pursue him until he came to the plains of Heshlon” (which is also the corrected reading in 𝓟).