Hey I'm in love with the look of this game and am currently working on a small game myself. I don't really know how I could manage a similar look as the one you have. If possible could you give me any tips or pointers as to how to achieve this?
There is a lot of info online that could better show you how to achieve PS1 Style graphics but some of the major constraints of the style are
Low resolution textures with limited color pallet, Low poly models(I used Blender and Sprytile), Limited Resolution (I scale the game to 320*240 with no aliasing), and Lo-fi Sounds (I just change the sample rate of recorded sounds to 8000 or 16000)
I recommend looking into the actual limitations of the PS1 and working with those limitations in mind.
There is also The Haunted PS1 Discord (their twitter has link in bio) which has a lot of devs also trying to achieve PS1 style in various engines so check it out if you are interested. Their game jams are the only reason I've finished my games!
I hope this helped wasn't sure how to answer this.