im having trouble with making a song sound fuller and more stereo, if that makes sense?

i dont know what it is called, but if you listen to the demo im gonna link here it just sounds flat! i cant figure out how to get it to sound bigger with stereo if that makes sense. so far theres a total of 6 tracks all different recordings as an attempt to make it bigger. im fairly new to using plugins and digital software ive lost an amp and recording software, but id like to know how to get it to sound bigger with clarity. i use REAPER to record and BIAS FX2 as a plugin for reaper. im just new to all of this but id like it to be as stereo and as smooth sounding as im able to. ive done recordings in the past with bandlab where it has got good stereo and sounds full but i just dont like the sound of their own distortion. || SONG LINK: https://www.bandlab.com/revisions/f70e07db-3794-4094-b444-1eefe8bcdbca?sharedKey=G\_LPlO3P8ESDHRfV0dPFcg ||