Chaining Power Amplifiers
The module you talk about has a supply voltage of 5 volts
It has a maximum output power of 100 mW
That's 2.24 volts RMS into a 50 ohm load
That's 6.32 volts p-p
That sounds about right for a class C output driver running on 5 volts

The problem isn't the addition of gains (dB) but the module running out of ability to produce more power on its output terminals due to only having a 5 volt supply.
Of course expectations of performance from goods supplied via ebay should be taken with a large pinch of salt especially if the device isn't &quot;backed&quot; by a decent PDF data sheet and some form of recognition that the manufacturer is bona fide and has adopted a minimum of quality standards during design and build.

Are those modules generally not suitable for TX power amplification or
would I need other modules?

I'm sure they are but their provenance is highly debatable

In general, can the Vpp output voltage outrank the supply voltage?

Yes with a class C output driver stage and a tuned collector tank.