Luckily there are a lot of options of eyepieces to add to your setup. They range in price from about $30 to several hundred.

Once you set a budget we can recommend some specific ones. Imo you can get away with 3 EPs, but you can get a full range of useful magnifications with only 5 EPs.

Some good options would be a 40mm and/or 32mm plossl. These Starguiders are very good for the price, and these 68° “redlines” aren’t half bad either.

I might suggest a 40mm and/or 32mm, 12mm, 9mm, and maybe a one more like a 20mm/18mm, 10mm, or 8mm. But start with the 32mm and 9mm, and build from there.