If you send in a tank or a formation of tanks alone into battle then yeah - anything will pick them off easily. That’s what we saw in Ukraine.
If you use proper combined arms doctrine where infantry, tanks, SHORADS, engineers, AD, gunships and Anti-tank infantry all travel together to support each other, then no, tanks are not sitting ducks.
Anything alone is going to fail - that’s the basic principle of combined arms. If you send infantry without armor cover they will fail, if you send UCAVs without ground support they will fail.
Pakistan and India have vast open terrain in the deserts and plains - there is no other effective way to cross it and take enemy land other than armor.
Anti-tank weapons and UCAVS evolve, so do tanks. New APS systems, drone jammers etc.