Will the Switch's successor outsell the original Switch? With the Switch set to become perhaps the best-selling console in the world. What are the chances of Nintendo's next console selling more than the Switch? sorry for my English

No need to apologize for your English.
I see very little chance of NG/Switch 2/whatever selling more than Switch. Switch is at 131.25 million and counting. 150 million seems like a lock at this point. In the all-but-guaranteed situation where NG is a hybrid, 80 million units seems to be the floor, but the ceiling could be around 150 million or so. But that's why I said ceiling for the 150 million figure. It could probably outsell Wii and PS1 and very likely even the Game Boy+Game Boy Color. But I expect a clear drop from Switch.
NG will surely capitalize on momentum from Switch, but it will almost surely not seem as new as Switch. Some Switch owners won't ever get one, even though there will also be some people who get NG who never had a Switch.

I see it being very successful as well, but I don't see a Switch 2 outselling the original (which I believe will end around 150 million). That being said, I can see the Switch 2 selling between 120-130 million, which would be amazing. Honestly, 120-130 is probably where the Switch would've ended if it wasn't for the covid bump (maybe 135-140m at best). 120m would put it above the Game Boy and above every PlayStation except PS2 (and possibly PS5, though I definitely think it's easier for the Switch 2 to exceed 120m than the PS5).

I can easily see Nintendo repeating the same decline with the Switch 2 as they did from the NES to SNES. At 150 million Switch's (give or take) that would put the Switch 2 around 115-120 million, which is still a staggering number. The Switch 2 will most likely be Nintendo's primary handheld once again and I don't see the floor of a Nintendo handheld being less than 80 million units at this point. It really will come down to software and how much of an upgrade the Switch successor is. If folks who jumped in this gen are fine and dandy with their OG Switch and it keeps getting material support from publishers and developers, the Switch 2 could have a harder road ahead of it. But considering the Switch is from 2017, I just don't see that happening. Nintendo couldn't have scripted a better opportunity for success after the Switch, at least in terms of timing and pacing. The onus is on them, of course, to release a compelling product and compelling software.

Who knows. The higher a console sells, the harder it is for the successor to match/exceed those sales. Plus we don’t know anything about Switch 2 yet. How much will it cost? Will it add something that brings in new audiences or possibly draws people away? How strong will the release schedule be? Will it have games that push boundaries like BotW or Mario Odyssey did or will they be conservative will new entries?

Yeah. An NES to SNES drop percentage (around 21%) or even a GB/GBC to GBA drop (around 31%) are both likely scenarios. I don't think we're going to see a DS to 3DS drop of around 49%, nor a horrendous drop like Wii to Wii U (over 86%). 

If Nintendo went back to two separate platforms a generation, we could easily get another Wii U-like failure. But as long as they stick with hybrids or handhelds, I think they're a long way away from selling that poorly again. 

You sort of answered your own question in the OP. Given the huge success of the Switch and given the fact that it could potentially be the highest selling console ever, it will be increasingly hard for its successor to outsell it.

I find it very unlikely but who knows really.

Really unlikely not only due to factors mentioned like the boost it got from the pandemic and how hard it is for a console to sell over 150 million but also due to it having more competition with the rise of handheld PC gaming. I can see at least a few million people who got a Switch not bothering with the successor and sticking to something like a Steam Deck instead and with how daunting a task outselling the Switch will be that by itself could make it not doable.

Easy guess is no. The Switch was phenomenon which benefitted both from the pandemic and a lot of very casual gamers. In the west I can see between 15% of Switchers owners not coming back to purchase any follow up console for the next decade. Anecdotal I know a lot of people who got a system out of curiosity/trend but barely touch it. Although newer markets could offset these once a decade console purchasers

I can see Switch 2 hitting 100/120m