Build Virtual Datasets from a list of existing datasets. More information: https://gdal.org/programs/gdalbuildvrt.html.
gdalbuildvrt path/to/output.vrt path/to/input_directory/*.tif
gdalbuildvrt -input_file_list path/to/list.txt path/to/output.vrt
gdalbuildvrt -separate path/to/rgb.vrt path/to/red.tif path/to/green.tif path/to/blue.tif
gdalbuildvrt -hidenodata -vrtnodata "0 0 255" path/to/output.vrt path/to/input_directory/*.tif