The kicking team (other than the kicker) start on the receiving team’s 40 on a normal kickoff instead of behind their own 35 like it used to be or on an onside kick.
https://operations.nfl.com/the-rules/rules-changes/dynamic-kickoff-rule-explainer/
Instead of an onside kick, I would have the option to go for the two-point conversion from the 5-yard line instead of the 2-yard line, and if you convert, you keep the ball and start from the 30 yard-line. So basically to keep the ball you must score a TD, a Field Goal does no good.