Improving RTD Sensor filtering and readout
Consider getting rid of the bridge and instrumentation amplifier. Feed the RTD (via 10k) from the same reference voltage that your ADC uses - this is called ratiometric measurements and removes one of the big error sources i.e. because RTD and ADC are both ultimately fed from a common reference voltage, it doesn't matter if that reference voltage drifts.

So, from memory a 1k RTD will have a resistance of 1000 ohms at 0 degC and about 1690 ohms at 100 degC. If your ADC reference voltage is 3.3 volts and the RTD is fed from 10kohm, the voltage change between 0 degC and 100 degC will be 0.300 volts to 0.477 volts. This is a change of 177 milli volts for a temperature change of 100 degC

Your ADC is 12 bit, therefore it has a resolution of 3.3 volts/ 4096 = 0.80566 mV.

So, for a 100 degC change, the input voltage changes 0.177 volts with a resolution of 0.80566 mV - this means your ADC can resolve 219.7 steps in a range of 100 degC OR, its actual resolution is about 0.5 degrees C.

This should easily obtain the accuracy you want.

By the way, you need to calculate the full range up to 200 degC but i don't see any problems in achieving that to the accuracy you want.

In short, reduce your errors by getting rid of stuff you don't need.

When it comes to filtering, sure use an external low pass filter but also filter in software by oversampling the signal and averaging.