Oh there is one other consideration when building a warlord, how do you make such a class not be too good to dip into? Especially while giving players warlord esque-abilities early enough to make them happy.
The only thing you need to be careful of is bonuses to a d20 roll (i.e. bless / advantage). Since those auto-scale.
It's also ok to allow some dipping. Warlords shouldn't be any better/worse then dipping monk, barbarian, or rogue.
Some appropriate 1-4 ideas.
Granting an attack for 1/2 damage is a cantrip level. Same as giving firebolt, it's ok for people to dip for it.
"The next ally who hits the target deals an extra 1d6 damage". Damage can Scale with warlord level.
Diplomacy Expertise, or Guidance, or other out of combat thing.
As a bonus action, 1 ally gain THP equal to 1/2 your warlord level.
As an action, 1 ally in reach regains 1 HP, that ally can only benefit from this once per short rest. Nice utility that is appropriate to dip for.
As a bonus action, 1 ally can move 1/2 it's speed as a reaction. Weaker, but more flexible cunning action.
At 5+ you get deep enough to get affect d20 rolls. Like bonus action to give everyone +1d6 to hit a target for at turn. Which works well as your serious power buff.
As you go up you can add breath to the d20 buffs like +1d4 to AC/Saving throw/DCs/skills/initiative. Maybe bump the bonus to +1d8 or doing it as a reaction (probably 11).
Also scaling the rest of your features, like 'mass' THP/movement grant, or granting cantrips and spells.
Not to mention the 5 ABI.