I rented an electric car (DS E-Tense) from Europcar in Frankfurt, Germany, in the first half of 2022.
First problem: the availability of cars. I had actually booked online to rent from Europcar Offenbach, as the Europcar website claimed that all stations have electric cars, only to be phoned by the Offenbach station days later to say that they didn't have any electric cars and that I needed to change my booking, which I did (to neighbouring Frankfurt). When I phoned Europcar customer service to complain, the person on the phone merely repeated that all offices have electric cars, despite me telling them that the Offenbach office told me otherwise.
The car came with a charging cable, which you need when charging at AC (slow) charging stations. DC (fast) charging stations come with their own cable.
You do need to plan your charging. I found that the distance indicated on the dashboard only applies in optimised conditions, such as cruise-control at 80 km/h in flat terrain in good weather. Drive 125 km/h on the motorway in winter weather, and you'll lose charge twice as fast. Don't assume you can reach that 175-km-away charging station just because the dashboard promises a 200 km range.
Another problem with charging is that most charging stations do not accept regular bank cards yet, but the card or app from the specific provider. You'll need to research what providers are common in the area and sign up to each of those. In some cases, you can use a card/app from one provider to pay for another, but you'll pay roaming fees. In other cases, you can't pay this way at all.
There are several route planners on the web. I used the one from goingelectric.de, which is in German, but others exist. Note that some databases are more complete in North-America and others are more complete in Europe. None are 100% complete, but the major charging stations should be present. There are also several smartphone apps you can and should use for your on-the-go planning. See this answer.
Prices vary a lot. Prices are highest for fast (20-minute) charging along the motorway, where one might pay as much as €0.80/kWh. It's cheaper at slow (3-hour) charging places near supermarkets and such. The cheapest is to charge at home. If you're lucky, your accommodation has a wallbox, but it may also be possible (but very slow, 24-hour+) to charge at a regular power outlet, if the electricity in the house is not too weak.