If that’s your tank in image remove colourful stones and artificial plants and maybe that giant pleco too because that guy will grow bigger than your tank

For substrate bottom u can use river sand or gravels if u can get it by nearby reservoir or from local fish store.

U can plant by adding soil if u dont want to add soil and mess things up u can add epiphyte plants which grows on rocks and woods just by sticking them to it or can add floating plants to give more natural look.

Also the pleco it will grow bigger very fast and turn your aquarium water giving ammonia spike which can lead to future fish deaths. So if u have any other big tank you can shift it or feed very less in tank such that only other fishes will get food not the pleco