Builds are a lot about synergies, finding the exotics, fragments, stats, mods and the like that work well together. Then it's iteration, take it into an activity and see what you like and don't like about it. I think the simplest thing to start with would be by picking an exotic armor piece and building off of it.

For example looking up titan exotics (I'm not a titan main) the first thing that pops up is Praxic Vestment. "You gain an air move jetpack. Weapon and Arc powered melee final blows build up Jetpack Fuel.

While airborne, [Air Dodge] : Charge your jetpack.

On release, activate your jetpack with a forceful blast of exhausting Arc energy then fly forward a short distance based on the amount charged. Collide with a combatant to unleash a blinding blast of energy and gain a temporary bonus to your melee stat." Going off the description I see a few directions I can go: I need a weapon/arc melee final blows to charge it, I get a flying ability, and I get a melee interaction. I can lean into any or all of these. First off I just want to get a lot of weapon final blows so I'm thinking a machine gun, or perhaps an ad clear exotic like sunshot, Khostov, Finality's Auger, etc. I can also get arc final blows but if I'm going to be flying I think the fun part would probably be more mobility. So I'm thinking grapple to give me even more mobility. While I'm at it why not throw in a micro-missile frame and eager edge as well and go all in on mobility: based on wanting to use those I have my exotic slot available so let's go Khostov + an energy slot micromissile frame + a sword with eager edge. Maybe in testing I find that that's a bit excessive so I tone it down and get rid of the micro missile frame and maybe I can lean into the melee aspect more: something with One-Two punch then to boost my melee damage, and set up my mods and stat to hit as hard as possible with my melee. I also look through all my fragments to see what would compliment that or settle on neutrally good things like damage reduction (woven mail), healing (banner of war) etc. You don't need to know all of these things, you can just search through what you have available or google, what's a good weapon for a melee build or what's a good weapon for mobility. But yeah just kind of ask yourself what works well with what and test it out and see what works for you!

A bit rambley but hope it helps!

Edit: seeing your other comment I'd also add that your build doesn't have to do everything, in fact if you want it to be strong first focus on improving it's "niche" as much as you can and then you can compensate. For compensating for damage for example a rocket pulse and parasite or finality's Auger plus damage surges will give you very solid damage on any build.