Looking to sell and buy

Hey all! Maybe someone in the real estate/mortgage world can answer a few questions for me. I know when you sell a house you get taxed in the end. But how much would you get taxed? Trying to figure out how much we would have to put aside if we sell and buy now. We bought our house years ago for $98,000, put down $10,000, so we had a $88,000 15 year mortgage. We have approximately $40,000 left to pay down. A couple of years ago we had a realtor walk through and give an estimate of about $250,000 for a resale in that market (2021) after some upgrades. Say we sell for $250,000 how would that be calculated? We have been looking at some houses and are about to see a potential one for 125,000. Does purchasing a second house immediately after selling our first effect it? I would love to talk to a local bank or realtor, but small town gossip mill moves fast. We are not announcing a move or listing our house until we have our ducks in a row. I hope this all makes sense!