How big can a fighter jet become until RCS becomes an issue? And why doesn’t bigger plane = higher payload capacity?

I’ve thought about it a lot. The famous comparisons of Russian fighter jets with western fighter jets. the size difference is enormous. The only worthy comparison though is Russia and the US. Because those other planes like the typhoon, Rafael, gripen etc are strictly meant for protecting their own borders, because they’re tiny countries with no ability or will or need to project power or do offensive strikes, far far far away.

But still, the comparison with Russian fighter jets and the US, both superpowers but completely different geographical and economical situation, are insane!

You can search up pictures yourself, it’s almost as if the Russian planes are real planes and the American ones are prototypes or trainers… But they aren’t.

And I guess the difference is because our economy is 30T gdp, and Russia’s is like 3T… and the difference geographical situation, Russia Being sooook huugeee, and we being so far away from the rest of the world and having forward bases everywhere.

Therefore Russia having a smaller budget, worse logistics, bigger size, would need to have a bigger plane, to have far longer range.

And that makes sense. But, when it comes to actual warfare, this plane then becomes a star in the middle of the night. The RCS is huge.

But I’m wondering, could you have a plane the size of the Su34, with the stealth of the f35? Or anywhere close?

The question I guess I’m asking is, how big can you make a plane and how much modern solutions can you use to minimize the RCS to the point it is comparable to our f35s?

Lets clarify. There’s a country in the world, they want to import the Su75 from Russia, but due to their geographical and economical needs they want one Su75 to pack a huge punch in terms of payload capacity and range. Thus, they’ll make one bigger than the original Su75 size. But, this country wants to be able to have some sort of 'strategic/battlefield chance' against all countries. Even against China, Russia or the US.

Meaning, if the country goes to war or meets up with American birds in the sky such as the f35, on paper, the plane should be able to stand a chance.

What type of solutions/modern solutions/compromises could such a nation take to minimize the RCS of the huge Su75?

Do you get the question?

Like, the country doesn’t have the economy the US has, nor the global forwarding bases the US has, nor a single aircraft carrier. But the country has a huge ambition to project aerial power outside its borders, they have tankers etc but want the plane to be almost independent. They want each Su75 to pack a huge punch, and get most out of the money.

The country have the following criteria for the import of the Su75:

5th gen.

Stealth almost comparable To F35/J35 (more than Su57?).

Have a range at least of the su35 (3600km, 4500km with external tanks).

And have a payload of atleast 11.000kg.

Is this possible?

And I’m also wondering, having looked up the numbers of the j20 j35 f35 f22 su35 and su57, almost all of these have a payload capacity of 8000-11000kg.

Then I looked up the f15ex and su34. And apparently the su34 only has a payload of 8000kg while the f15ex has one of the 13400kg.

Why does russias plane almost get the same level of payload as the US, while being almost 3x as big?

and no I’m not 'crazy', I’m just extremely interested in the subject and not a single person I know is interested in stuff like this…..