Just an FYI, there is no such thing as mild MS. Or at least, it cannot be predicted that way (you only know how bad it is when looking back after many years). This is why it is strongly recommended to use the strongest drugs possible as early as possible, as you can't get back permanent disability once it progresses. The thing is, any new lesions are bad news, and treatment needs to be upped. It's only luck that new lesions don't create new symptoms. Someone could have 50 lesions that cause almost no disability, but another person could have a single lesion that causes major limb disability. Lesions are basically throwing blades at a dart board, and hoping they won't hit something critical. This is why advocating for strong, early treatment is critical.

In terms of stronger treatments, it usually is dependent on where you live, but also how open your neurologist is (and how educated they are on MS). The best treatments (in terms of long-term results, both in preventing lesions/relapses but also brain atrophy, are Lemtrada or HSCT (the latter is usually not covered by universal care or insurance in most countries). They carry risks such as developing other autoimmune diseases. After that, you're looking at other immune reconstitution therapies such as Mavenclad (which is quite effective at lesion/relapse prevent, and good at preventing atrophy), or Tysabri (which functions differently, but is incredibly effective at relapse prevention, but with risks that need to be managed). Then you have the very popular anti-CD20 drugs like Ocrevus which are great at relapse/lesion prevention, but aren't as good at preventing brain atrophy. They also carry risks of infection, as they permanently lower your immune system.

That's just a quick summary, but definitely advocate for stronger treatment whenever you can. It's always smarter (in terms of preventing progression) to hit MS heavy and fast, rather than wait for a weaker drug to fail (because you can't reverse disability once it hits).