If both competitors don't agree to cancel the jumpoff, it will proceed as the default, and either competitor can forfeit the jumpoff (effectively "refusing" the jumpoff) making themselves the 2nd place finisher and the other athlete the winner.
26.8.1 The athlete with the lowest number of jumps at the height last cleared shall be awarded the higher place.
26.8.2 If the athletes are equal following the application of Rule 26.8.1 of the Technical Rules, the athlete with the lowest total of failures throughout the competition up to and including the height last cleared, shall be awarded the higher place.
26.8.3 If the athletes are still equal following the application of Rule 26.8.2 of the Technical Rules, the athletes concerned shall be awarded the same place unless it concerns the first place.
26.8.4 If it concerns the first place, a jump-off between these athletes shall be conducted in accordance with Rule 26.9 of the Technical Rules, unless otherwise decided, either in advance according to the regulations applying to the competition, or during the competition but before the start of the event by the Technical delegate(s) or the Referee if no Technical delegate has been appointed. If no jump-off is carried out, including where the relevant athletes at any stage decide not to jump further, the tie for first place shall remain. Note: This Rule 26.8.4 does not apply for a Combined Events Competition.
Rules source: https://www.worldathletics.org/download/download?filename=febae412-b673-4523-8321-e1ed092421dc.pdf&urlslug=C2.1