It is very difficult in a developing country because of indiscriminate solid waste dumping. The best is to sort and compost organic while at the same time combusting others like paper.

In Belgium, enhanced landfill mining is a trendy subject. They have organized international symposiums (last one in 2020) which could inspire you: https://elfm.eu/

Recycling is key, sorting is also important (bury same kind of wastes together to ease for future mining/knowing where your waste are precisely, and in what quantity).

I know some research is also carried out by accelerating the decomposition process of organic wastes (ingest in the landfill bacteria & water, such as within the MINERVE project in Belgium) and capturing the methane produced for energy production.

Obiousvly, lowering the waste input is part of the solution...

Is landfilling unavoidable, the waste can be pretreated to reduce the organic compounds and the waste can be layerwise installed and strongly compacted to reduce the landfilling space.

you should consider your situation ..and tailor the solution based on your case (city people behavior, regulation, operation as well as operational issues)..

thus there is no magical solution but in general the following are some strategies:

1- start from reducing the waste from generation point (at source segregation and recycling)

2- use the MRF, or segregate the recyclable materials at landfill

3- landfill mining

4- increase the depth of waste disposal considering the shear and slides of the waste.

5- use waste compactors

6- use organic waste composting

7- use waste incinerator reduce the waste volume by more than 90%

8- dig a waste ditch ..but not to dump the waste overland.

9- good landfill management ..by reserving a zones for bulky waste (demolition, bulk E-Waste...)