For a start Russia already has a Baltic state: https://en.wikipedia.org/wiki/Kaliningrad_Oblast and, not only that, has access to the Baltic itself. So there's zero geopolitical strategic advantage.

Anywhere that Russia has "annexed" has had a majority ethnic Russian population and historical ties to Russia. Estonia, Latvia, and Lithuania are not majority ethnic Russian, do not speak Russian, and are part of the EU (and NATO) so they're clearly not aligned geopolitically with Russia and it would cause major regional ramifications, undoubtedly triggering a war with NATO, and/or the EU (both nuclear entities). It would be wholly unprecedented in modern times.

> think Russia would annex a Baltic state

Baltics and Crimea are not comparable. - Crimea has Russia's only warm water port and would never be given up - Russia already has Baltic access (Kaliningrad and StPetersburg) - Crimea has been majority ethnic Russian for centuries and welcomes Russia - Baltics hate Russia

In summary, there is absolutely no logical reason Russia would annex Baltic state.

However, there are plenty reasons why non-Russian interests always repeat this narrative.

Russia doesn't need Baltic states. Their ports lost their value and the population is dying from poverty, drug addiction and alcoholism (fertility rate in Baltic states under EU is significantly lower compared to soviet times).

Why would Russia need several bankrupt dying states? To feed and develop them like in Soviet times getting nothing but hatred in response? Ditto for Ukraine BTW.