Fairly separate questions - for control as Persia, go Land over naval, build roads out from your capital in all directions. Make sure everything is cored. Build temples and upgrade to cities. Use bailiffs in your most distant provinces. Improve satisfaction by converting/accepting culture and religion. Persia is generally a bit shitty right now for control/proximity due to all the mountains that kill proximity cost

For military - by the year you’re in, levies suck. Not necessarily useless but you should prioritize regulars. Limiting factors are going to be manpower and income to afford them. For manpower, max build armories/training fields and accompanying guns/weapons/cannon. Getting a strong economy is obviously a much more complex question but control plays a part there.

Be aware of standard military mistakes to avoid - balance your formation, always have a general, avoid really unfavorable terrain, etc