QoL: PCs can choose to permanently drop down the initiative order
I believe this was just a thing you could do in older editions but there are no rules for it in 5e. Sometimes going first doesn't work well for teamwork (e.g. your Shield Master going directly before the enemy so they get up after each shove before anyone can attack them while they're prone), so letting you drop down the order can help without giving you a freebie (i.e. the enemy might get an extra go against you). I've not encountered any problems with this yet!