You can do so by including "mosaickingOrder": "leastRecent" in the data part of your request. An example curl request is below.
curl -X POST https://services.sentinel-hub.com/api/v1/process \
-H 'Content-Type: application/json' \
-H 'Authorization: Bearer <YOUR_TOKEN_HERE>' \
-H 'Accept: application/tar' \
-d '{
"input": {
"bounds": {
"bbox": [
12.44693,
41.870072,
12.541001,
41.917096
]
},
"data": [
{
"dataFilter": {
"timeRange": {
"from": "2023-02-15T00:00:00Z",
"to": "2023-08-09T23:59:59Z"
},
"mosaickingOrder": "leastRecent"
},
"type": "sentinel-2-l2a"
}
]
},
"output": {
"width": 779.8034286939699,
"height": 523.469,
"responses": [
{
"identifier": "default",
"format": {
"type": "image/tiff"
}
},
{
"identifier": "userdata",
"format": {
"type": "application/json"
}
}
]
},
"evalscript": "//VERSION=3\n// Script to extract a time series of NDVI values using \n// Sentinel 2 Level 2A data and metadata file.\nfunction setup() {\n return {\n input: [{\n bands: [\"B04\", \"B08\"],\n units: \"DN\"\n }],\n output: {\n bands: 1,\n sampleType: SampleType.FLOAT32\n },\n mosaicking: Mosaicking.ORBIT\n }\n \n }\n \n // The following function is designed to update the number of\n // output bands without knowing beforehand how many there are\n function updateOutput(outputs, collection) {\n Object.values(outputs).forEach((output) => {\n output.bands = collection.scenes.length;\n });\n }\n // function to generate a json file with a list of the NDVI \n // dates used in the analysis. \n function updateOutputMetadata(scenes, inputMetadata, outputMetadata) {\n var dds = [];\n for (i=0; i<scenes.length; i++){\n dds.push(scenes[i].date)\n }\n outputMetadata.userData = { \"acquisition_dates\": JSON.stringify(dds) }\n }\n \n function evaluatePixel(samples) {\n // Precompute an array to contain NDVI observations\n var n_observations = samples.length;\n let ndvi = new Array(n_observations).fill(0);\n \n // Fill the array with NDVI values\n samples.forEach((sample, index) => {\n ndvi[index] = (sample.B08 - sample.B04) / (sample.B08 + sample.B04) ;\n });\n \n return ndvi;\n }"
}'
You can also set this in the Request Builder by enabling Show Advanced Options under Data Collections as shown at the end of my reply to your question.
Please do go through the very descriptive documentation and API Reference available to make it easy for the users to create their own requests.