I notice the words “dual 18650” which I didn’t see earlier. Same comment about batteries still applies but now is much easier to achieve because the per battery requirement gets cut in half. Just about any dual 18650 should do 90w with even mid drain rate batteries in it. Your issue is now “small”. The difference between a “small” dual 18650 mod and a “large” one just isn’t that great. One needs a certain amount of space for batteries and a certain amount of space for mosfet. After that it’s all arrangement. There are two general methods: online where the batteries and mosfet are placed in a row like the ageis, and where they form a sort of triangle, like the battle stars and wismecs. At that point it becomes a question of what fits your hand best and how much width they have at the top to take an atty. some inline ones are quite narrow but the result is they can only take 22mm attys. The ageis is quite large, and can take a 30mm atty. some triangle format devices have centrally located pins and can take large attys, some have them off to one side and can’t.
It all depends on what you want.