The original manuscript is not extant here, but spacing between existing fragments indicates that initially in 𝓞 the that was probably not there, although it could have been supralinearly inserted by Oliver Cowdery. In the printer’s manuscript, Oliver wrote this passage with the that. It is possible that he accidentally added the that during the copying process. The critical text will follow the earliest extant evidence (the reading of 𝓟), thus maintaining the that here in Alma 63:4.
Summary: Maintain in Alma 63:4 the that after “and it came to pass”, the reading of 𝓟 (here the earliest extant source).