Regarding the headlights, there's some totally wrong answers up above. You only need headlight beam adjusters if your headlights illuminate the left side of the road. From the RX400h onwards the headlights are 'flat' i.e. they do not light up the left side of the road any higher than than the front. Flat headlights do not need beam adjusters.
There are more and more low emission zones every year, I've found the best advice on the AA website as they have very clear country specific advice like this and links to all the sites you need to buy lez stickers, vignettes, toll devices, etc: Driving in France and Monaco | AA (theaa.com)
My wife is from Slovakia so we've driven there every summer for the school holidays for the last decade or so (barring one pandemic year) so I have to do the research each year
Other gotchas - dashcams: Austria doesn't allow them at all. SatNavs: France doesn't allow speed camera data. Vignettes: many are available online nowadays. LEZ stickers: take a long time to arrive and don't always turn up - order early*
French tolls can be sped through with a device but getting one in the UK is a bit of a pain and you have to pay an annual fee even if you don't use it at all - you can pay with a contactless card which is as quick as you can get otherwise
Simplest advice: always check the regulations for each country before you go
*To avoid cluttering your windscreen with stickers buy some 3 inch/7.5cm round acrylic disks and attach the stickers to those then hang them on the window with clips:
Disks: XIWENQUKU 10Pcs Clear Acrylic Sheet 0.04 Inch Thick Acrylic Plastic Disc Transparent Round Acrylic Panel Circle Acrylic Sheets Sign for Picture Frame Painting DIY Crafts (3 inch / 7.5 cm) : Amazon.co.uk: Home & Kitchen
Clips: Wicked Chili 4x Parking Permit, Ticket and Note Holder for Car Windscreen, Clips with Removable Suction Cup, Avoid parking fine, Set of 4 (Made in Germany) transparent : Amazon.co.uk: Automotive