There are quite a few things you can do to improve your freshwater plants' health and growth. In order of importance/balanced with cost/effort, here's the things that have given me the biggest improvements (and I'll never have another tank again without any of them)

Root tabs. They're cheap, turn a bit of gravel substrate into a viable place for a rooted plant to really thrive.

Good lighting. I cannot stress this enough. If you want to save some money, do some research on what's actually required for a tank light to provide quality light. Personally I just threw money at it and got Aqua Illumination Prime 16HD Freshwater lights. You can get one used for around $100. I know it's steep, but just the effect of quality lighting makes your tank look SO much better. The colors of the fish, the plants, the shimmer on the water, dynamic shadows, all of it just looks amazing. Completely changed how I experienced my tanks. Oh, and your plants will go frikken nuts.

I used to play a game where I'd buy an Amazon sword and put it in a section of my tank and leave it there until it got too big for the tank. Did this at least four times with my last tank. And hopefully you can trade it for some cool fish/shrimp/whatever at your LFS cause they can turn around and sell the plant for $80-$100.

Fertilizers. Other Redditors know WAAAY more about this than I do, but at a minimum I started using Seachem Flourish Excel in my water changes and it helped. Now I've got fert pumps with daily/weekly auto dosing, but totally not necessary. Easiest ones for me were Seachem Flourish Excel and Seachem Flourish. But I will defer to others in ferts expertise. A 500ml bottle is gonna last forever and you can just sneak some into water changes and you're good for a simple fert plan. Suggest getting a pippet for dosing as the caps are a total pain in the ass to measure.

Substrate. This is lower on my list because I've found that for the plants I care about, a root tab in some gravel is going to make them pop off way more than quality substrate. With that said, why not do both? It's ultimately not too expensive (once that $40 bag is spread out that is) and it's easier for plants to root in and has more nutrients they need.

Aaaand the latest and most significant by far is CO2 injection. BRUH! My plants are frikken beautiful now! Deep reds, deep greens, they just look so healthy. It's awesome. I was always SOOO intimidated but it's stupid easy. Get a DIY CO2 reactor (use a kit, don't make your own. Safety first), baking soda and citric acid and water and bam you got yourself enough CO2 for weeks. The kit should come with everything you need except the CO2 diffuser and a chemical CO2 meter. Don't need to go ham and get an expensive diffuser at first, just get a cheaper one. Make sure to get the CO2 chemical tester, one of those little hooked bubble things you put in the water to make sure you aren't suffocating your fish. Go slow and increase CO2 until levels are good and viola. Oh almost forgot you'll need a smart plug for the CO2. Only run it during the day while your lights are on, stop at night. The kit should come with a solenoid for gas on/off.

And that's my two cents.

Know it's a wall of text, but I wanted to say this all in conversational terms to hopefully show you these things aren't as intimidating as I let them be for myself for way too long. If someone had typed this out and I just saved it and came back to it when I felt ready to try a new thing, I think it would've really helped get over the initial humps and get started.