MCP73831 charger - how to control low voltage cell
The charger is a charger - not a battery management IC.
As the battery IS the output the IC cannot disconnect the load regardless of its functionality.
The UVLO action is detailed on section 4.1 of the datasheet.
UVLO is asserted if Vin is less than about 3.4 V (see datasheet page 3).
You COULD use this feature in conjunction with an output switch and battery voltage sensing and possibly voltage offsetting BUT this would be a very complex approach given that there are existing devices that do what you want.
Your question is phrased in terms of &quot;how do I make this solution fit my need&quot;. A preferable approach is to fully specify your requirement and ask for solutions. By all means also then suggest possible solutions and tell us what you have attempted and thought of.
You need to supply all available information - web links if available - battery capacity and model, target charge rates, input supply characteristics,  more ... .
It may be that low cost off the shelf TP4056 modules with separate battery and Vout ports do what you want. Until we know what you actually want this cannot be guaranteed.

TP4056 battery cutoff voltage alteration.
Summary: Lower the &quot;battery&quot; voltage seen by DW01 so that  higher low-battery threshold is achieved.
The circuit diagram of a typical TP4056 modules with included low battery isolation is given below.
You'd need to look at the DW01 data sheet (which is available) to be sure but 'at a glance' it appears that by putting a resistive divider on pin 5 of the DW01 to lower the voltage that it 'sees' that you may be able to raise the low battery cutoff voltage.
Failing that, adding a comparator on pin 5 that switches when target Vbat_low is reached would allow any desired low battery value above the original one to be set.