Joe Snow's place is a good starting point.
https://www.joesnowaquaticplants.com/I am not sure if Joe is still in business, but he did put together an excellent website.
Click on the link, and then click on the text that says "Aquatic plants available". He has the common name and the latin name for probably 50 pond plants, along with a good picture and a brief description of their growth habits.
If you see something you like, I would research it more on wikipedia. THEN try to find a source that sells the item you like.
The aquarium supply companies like:
https://aquariumplants.com/can also sell small versions of plants. If you pick the correct species for your habitat, they can grow to fill your pond's niches.
Finally, I would suggest searching for the people that build koi ponds and water features in your area. They will either be able to sell you some water plants themselves, or perhaps be able to direct you to their wholesaler.
P.S. Another option is to add a few plants to your pond that are notorious for spreading, but only do so via their root systems (by rhizomes, stolons, or tubers). Put these plants in large plastic planters that you sink at the preferred water depth for your chosen plant. This might allow you to have an attractive, but invasive, type of water lily that you would be able to keep under control.
DO NOT do this for aquatic plants that spread by fragmentation.
Good luck on your project!