I get this weird sense of unreality when parents of multiple children seriously consider whether to have #3, 4 etc in 2023. Do you not keep up with world affairs? It's not really about whether you are able to afford or have space for a 3rd, 4th or 5th child now, or in 5 or 10 years time, but whether society, which will likely look very different by the time next year's babies are young adults, will be able to sustain our progeny at anything like the standard of living we are accustomed to, in even the most moderate households.
My DC are older and I am working my butt off to ensure they enter adulthood with as much support as I can muster in terms of housing, finance and the means to earn a living in an increasingly unstable workplace, because the future is going to be a tough gig, on account of international conflict, increasing political tensions, global economic stressors and a warming climate. In a globalised growth economy, we are no longer insulated from impact in any significant way.
In addition, I think PPs who have mentioned the time factor are spot on. Purely anecdotally, from my professional experience, children with multiple siblings rarely get the same amount of unhurried, open-ended, luxuriously focussed 1:1 time as onlies or children with one sibling. They may do lots of lovely things as a family group, but seem to crave the 1:1 so much. I've stopped at 2, but still feel like my DC would benefit loads from even more quality 1:1 time than I already give them, and I've always tried to give each of them at least an hour each a day.
I'd really try to find a feeling of completion with the family you already have.