I own a hobby shop and have had 30+ years experience using both model paints and store-bought enamel and laquer paints.
Many model paints are enamels, but a majority of brands now are going to acrylics. All of your model spray paints are enamels or solvent based. The acrylics can be durable though. They aren't like poster paints that soften up when wet. Once they are dry they are permanant and quite hard to remove. They can me harder to strip or remove than enamels.
The potential problem with model enamel paints is that they are somewhat soft compared to more industrial paint jobs. Its hard to polish and buff enamels like you can lacquers or harder paints. You just wear through them if you aren't careful. Some colors like metallics can be very soft and don't dry well... they will be tacky for months and will leave finger prints or rub off on your fingers.
Clear coats work very well. Clear coats can change the color of metallics. Silver will turn grey for example. Some of the better clear coats are lacquers but those will blister and craze enamel and acrylic paints. Compatability is a big problem if you aren't careful.
You might potentially have problems with cracking due to flex in the racquet. The paints aren't desinged to flex. Letting the base coat dry a long time (few weeks) before applying any kind of clear coat will help. THen let the clear coat dry.
For the average person wanting to repaint a racquet I would recommend the Tamiya brand of spray paints and primers. Their spray paints are plastic-safe lacquers. They go on VERY smoothly, without runs, drips, splattering, etc. I use an airbrush a lot, but when I want simple, one-color finishes, I always use the Tamiya sprays. Plus they dry very quickly. The metallic colors are also excellent. They offer the usual gold, silver, aluminum shades, but also gunmetal, dark gunmetal, metallic blue, metallic red, metallic green, etc., and also clear colors to apply over metallics for a candy finish.
I would prime the racquet with Tamiya's super fine white spray primer. Especially if you want to paint it in a light or bright color. Any nicks or scratches can be filled with their liquid white brush on primer and lightly sanded out. Then apply the colors of your choice iwth the sprays. Tamiya's own brand of tape is excellent for masking. Its flexible and if you apply it right, you won't get paint creep. You can also decant the spray cans and airbrush the lacquers. They even brush paint well for little touch ups.
Paint rules of thumb... acrylics go over any finish. You can apply enamels over acrylics or lacquers. Lacquers will melt acrylic or enamel paints
With an airbrush you can paint some lacquers over other paints becuase they go on very thin and dry quickly.
For a clear coat, on Tamiya paints I recommend their own clear gloss Spray. Several thin coats followed by a heavy wet coat give a beautiful high gloss.
Future Floor Wax (Johnsons Klear outside the USA) is also an excellent high gloss clear. Check on a site like hyperscale's aircraft modelling board for Future tips. You can airbrush it, dip things, etc.