As long as the battery fits, there is nothing wrong with replacing one with another with a slightly larger Ah capacity. Theoretically yes, but practically no. Every UPS is designed to charge a particular type of battery. The power capacity of the battery is chosen to cater to the power output of the UPS
There's nothing wrong with swapping out a battery with a little higher Ah capacity as long as it fits. Yes, in theory, but no, in practise. Each UPS is made to charge a certain type of battery. The battery's power capacity is selected to match the UPS's power output.